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Educational policy analysis archives.
n Vol. 11, no. 15 (May 08, 2003).
Tempe, Ariz. :
b Arizona State University ;
Tampa, Fla. :
University of South Florida.
c May 08, 2003
Teaching children to read : the fragile link between science and federal education policy / Gregory Camilli, Sadako Vargas [and] Michele Yurecko.
Arizona State University.
University of South Florida.
t Education Policy Analysis Archives (EPAA)
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1 of 51 Education Policy Analysis Archives Volume 11 Number 15May 8, 2003ISSN 1068-2341 A peer-reviewed scholarly journal Editor: Gene V Glass College of Education Arizona State University Copyright is retained by the first or sole author, who grants right of first publication to the EDUCATION POLICY ANALYSIS ARCHIVES EPAA is a project of the Education Policy Studies Laboratory. Articles appearing in EPAA are abstracted in the Current Index to Journals in Education by the ERIC Clearinghouse on Assessment and Evaluation and are permanently archived in Resources in Education .Teaching Children to Read : The Fragile Link Between Science and Federal Educat ion Policy Gregory Camilli Sadako Vargas Michele Yurecko National Institute for Early Education Research and Rutgers UniversityCitation: Camilli, G., Vargas, S., and Yurecko, M. (May 8, 2003). Teaching Children to Read : The fragile link between science and federal educ ation policy. Education Policy Analysis Archives, 11 (15). Retrieved [date] from http://epaa.asu.edu/epa a/v11n15/.AbstractTeaching Children to Read (TCR) has stirred much controversy among reading experts regarding the efficacy of phonics i nstruction. This report, which was conducted by the National Reading Panel ( NRP), has also played an important role in subsequent federal policy rega rding reading instruction. Using meta-analysis the NRP found that systematic phonics instruction was more effective than alternatives in teaching childr en to read. In the present
2 of 51study, the findings and procedures leading to TCR w ere examined. We concluded that the methodology and procedures in TC R were not adequate for synthesizing the research literature on phonics instruction. Moreover, we estimated a smaller though still substantial effect ( d = .24) for systematic phonics, but we also found an effect for systematic language activities ( d = .29) and tutoring ( d = .40). Systematic phonics instruction when combin ed with language activities and individual tutoring ma y triple the effect of phonics alone. As federal policies are formulated a round early literacy curricula and instruction, these findings indicate that phonics, as one aspect of the complex reading process, should not be overemphasized. The data files that serve as the basis of this arti cle are available for download. Executive SummaryIn 1997 the U.S. Congress directed the Director of the National Institute of Child Health and Human Development (NICHD), in cons ultation with the Secretary of Education, to establish a national pan el on research in early reading development. The panel, now known as the Na tional Reading Panel (NRP), was charged with conducting a thorough study of the research, determining what research findings were suitable fo r classroom application, and recommending methods of dissemination. Six area s of reading were eventually examined, and an influential report was released in December 2000. This report, Teaching Children to Read has stirred much controversy among reading experts, and both critics and support ers have been highly visible in national-level venues. Without question, the report has played an important role in subsequent federal policy regardi ng reading instruction. One of the six areas of reading research examined b y the NRP was phonics instruction. According to the NRP: An essential part of the process for beginners invo lves learning the alphabetic system, that is, letter-sound corres pondences and spelling patterns, and learning how to apply this k nowledge in their reading. Systematic phonics instruction is a way of teaching reading that stresses the acquisition of l etter-sound correspondences and their use to read and spell wor ds . (NRP, 2000b, p. 2-89). Using a research methodology known as meta-analysis the NRP identified 38 experimental and quasi-experimentalmeaning a re asonably close approximation to experimentalresearch studies on p honics instruction. (A meta-analysis can be thought of as a quantitative l iterature review.) Based on a statistical averaging of the outcomes from thes e 38 studies, the NRP concluded that their findings provided solid suppo rt for the conclusion that systematic phonics instruction is more effective th an alternatives in teaching children to read. Altogether, eleven conclusions we re offered regarding the efficacy of phonics instruction, but the above find ing is of prime importance.
3 of 51In their deliberations on research findings, the NR P clearly recognized the ultimate need for instructional decisions to be bas ed on the best empirical evidence and methods of analysis. The NRP recounted that one theme expressed repeatedly, at a series of five regiona l public hearings held prior to its work, was the importance of high standards f or choosing evidence about what works in reading instruction. The NRP in terpreted this to mean that experimental and quasi-experimental studies we re most likely to contain reliable, valid, and replicable findings. However, two aspects of the scientific method are important and should be distinguished. T he review process, i.e., meta-analysis, is a set of procedures for distillin g conclusions and generalizations from research studies. In contrast, the standards of scientific evidencewhich led the NRP to focus on experimenta l studiesdetermine what evidence will be included in the meta-analytic process. For the purposes of this review, we were primarily concerned with the former aspect, that is, the research review process Most currently available reviews of the NRPs study have focused on the interpretation of the results for phonics instruction while assuming the basic co rrectness of the measurement and analytic procedures. We did not mak e such assumptions; rather, we designed an independent study in an atte mpt to reconstruct the NRPs central findings. As in other types of scient ific investigation, replicability is a key criterion for judging the cr edibility of the NRP meta-analysis, and consequently how seriously we sh ould consider applying its findings.We began with the same 38 studies analyzed by the NRP, but in the course of our analysis, we deleted one study and added thr ee. We then devised alternative plans for extracting and analyzing data from 40 studies (38 1 + 3 = 40). Based on these analyses, conclusions were drawn and interpretations made regarding the efficacy of phonics instruction. Though some of the methodological steps taken by the NRP analysts were retraced, our goal was to verify whether an independent team of researcher s would arrive at conclusions consistent with those in the NRP report We did not examine how the original 38 studies were chosen. It would h ave been useful to examine the full range of the NRPs procedures and findings, including study selection, but this task would have required resources well beyond our means.In our analyses, we found that programs using syste matic phonics instruction outperformed programs using less systematic phonics with d = .24. Though this effect is statistically significant, it was su bstantially smaller than the estimate of the NRP at d = .41. (Roughly speaking, d = 0 means no effect; d = .5 is moderate; and d = 1.0 is large.) The systematic phonics effect, moreover, was smaller than the effect for individua l tutoring ( d = .40). Students receiving tutoring had one-to-one instruct ion as opposed to instruction in small groups or classes. We also fou nd that students who received systematic language activities did better ( d = .29). This effect is comparable to that of systematic phonics instructio n. In addition, standardized tests tended to give larger effects th an locally developed
4 of 51instruments ( d = .19). Overall, we concluded that there is reason to believe that these effects are additive. Systematic phonics instruction when combined with language activities and individual tu toring may triple the effect of phonics alone.Though language activities were included in over 30 % of the treatment conditions in the 38 studies, the NRP analysts miss ed the language effect for one simple reason: they didnt look for it. In our opinion, an approach that recognizes the complexity of reading instruction ha s the potential to improve the estimates of average effect sizes in all substantive areas that the NRP examined including: phonemic awareness instruction; fluency; comprehension; vocabulary instruction; text compreh ension instruction; teacher preparation and comprehension; strategies i nstruction; teacher education and reading instruction; and computer tec hnology and reading instruction. To obtain more accurate estimates of t he full range of variables that influence reading, analyses would also benefit from, and indeed may require, a substantially larger sample of studies. In this effort, researchers with substantive, methodological, and classroom exp erienceas well as time and resourcesare necessary to find studies, a nd to propose and test alternative design strategies. While we applaud the NRP for taking the challenging and difficult first steps in summarizin g the extant knowledge on reading instruction, it is clear that substantial r esources will be required for completing this essential work.If the NRP results are taken to mean that effective instruction in reading should focus on phonics to the exclusion of other c urricular activities, instructional policies are likely to be misdirected This interpretation of the data results from a design in which simultaneous in fluences on reading interventions were not adequately coded and analyze d. In particular, early literacy policies are a timely concern, especially as they are interpreted and applied in the federal Early Reading First Program. Program administrators and teachers need to understand that while scientif ically-based reading research supports the role of phonics instruction, it also supports a strong language approach that provides individualized inst ruction. As federal policies are formulated around early literacy curri cula and instruction, it is important not to over-emphasize one aspect of a com plex process. Fletcher and Lyon (1998) wrote a targeted skill cannot be l earned without opportunities for practice and application. With t his common sense observation in mind, it is not surprising that the research shows a balance of systematic phonics, tutoring, and language activiti es is best for teaching children to read.IntroductionIn 1997 the U.S. Congress directed the Director of the National Institute of Child Health and Human Development (NICHD), in consultation with the Secretary of Education, to establish a national panel on research in early reading devel opment. The panel, which is now known as the National Reading Panel (NRP), was charged wi th conducting a thorough study of the research, determining what research findings were s uitable for classroom application, and recommending methods of dissemination. Five areas o f reading were eventually examined,
5 of 51and an influential report was released in December 2000. This report (NRP, 2000a), Teaching Children to Read (Note 1) has stirred much controversy among reading expert s, and both critics and supporters have been highly vi sible in national-level venues (e.g., Manzo, 1998; Pressley & Allington, 1999; Yatvin, 20 00; Krashen, 2000, 2001; Garan, 2001, 2002; Ehri & Stahl, 2001; Shanahan, 2001; Coles, 20 03). In any case, the report has played an important role in subsequent federal policy rega rding reading instruction (Manzo, 2002; Manzo & Hoff, 2003).One of the five areas of reading research examined by the NRP was phonics instruction. According to the NRP: An essential part of the process for beginners invo lves learning the alphabetic system, that is, letter-sound correspondences and s pelling patterns, and learning how to apply this knowledge in their reading. Syste matic phonics instruction is a way of teaching reading that stresses the acquisi tion of letter-sound correspondences and their use to read and spell wor ds . (NRP, 2000b, p. 2-89). Using a research methodology known as meta-analysis the NRP identified 38 experimental and quasi-experimental (meaning a reasonably close approximation to experimental) research studies on phonics instruction. Based on a statistical analysis of the quantitative results from these 38 studies, the NRP concluded th at: Findings [from the meta-analysis] provided solid su pport for the conclusion that systematic phonics instruction makes a more signifi cant contribution to childrens growth in reading than do alternative pr ograms providing unsystematic or no phonics instruction. (NRP, 2000b p. 2-132) Altogether, eleven conclusions were offered regardi ng the efficacy of phonics instruction, but the above finding is of prime importance.In their deliberations on research findings, the NR P clearly recognized the ultimate need for instructional decisions to be based on the best emp irical evidence and methods of analysis. At a series of five regional public hearings held p rior to its work, the NRP recounted that one theme expressed repeatedly was The importance of applying the highest standards of scientific evidence to the research review process so that conclusions and det erminations are based on findings obtained from experimental studies charact erized by methodological rigor with demonstrated reliability, validity, repl icability, and applicability. (NRP, 2000a, p. 12) Two aspects of the scientific method should be dist inguished in this desideratum: the research review process, and the standards of sc ientific evidence that led the NRP to focus on experimental studies.In this document, we are primarily concerned with t he former aspect, that is, the research review process. Most currently available reviews of the NRPs study have focused on the interpretation of the results for phonics instruction while assum ing the basic correctness of the measurement and analytic procedures. We did not make such assumptions; rather, we designed an independent study in an attempt to reco nstruct the NRPs central findings. As in
6 of 51other types of scientific investigation, replicabil ity is a key criterion for judging the credibility of the NRP meta-analysis, and consequen tly how seriously we should consider applying its findings.We began with the same 38 studies analyzed by the NRP, but in the course of our analysis, we deleted one study and added three (Note 2) others originally identified by the NRP. We then devised alternative plans for extracting and a nalyzing data from the 40 studies (38 1 + 3 = 40). Based on these analyses, conclusions were drawn and interpretations made about the efficacy of phonics instruction. Though some of the methodological steps taken by the NRP analysts were retraced, our goal was to verify whether an independent team of researchers would arrive at conclusions consistent with those in the NRP report. We did not examine how the original 38 studies were chosen. It would have been useful to examine the full range of the NRPs procedures and findings, in cluding study selection, but this task would have required resources well beyond our means Our investigation resulted in several major finding s. We obtained a statistically significant effect for systematic phonics instruction, but one that was substantially smaller than that of the NRP. Relative to systematic phonics, we also fo und that individualized instruction (i.e., tutoring v. small group or class) had a substantial ly larger effect while language-based instructional activities yielded a comparable effec t. Finally, we concluded that there is no reason to believe that these effects are mutually e xclusive. Systematic phonics instruction when combined with language activities and individu al tutoring appears to have a much larger effect than phonics alone.The remainder of this report consists of seven sect ions: Introduction to Meta-Analysis. A brief introduction to meta-analysis is given. I. Findings of NRP Study. An overview of the NRP findi ngs on phonics instruction is given along with select results. II. Reanalysis: Research Questions and Methods. Questio ns examined by the current study are listed, and methodological issues are des cribed. III. Re-Analysis: Results. Quantitative results of the p resent study are given. IV. Re-analysis: Discussion. The size of the phonics ef fect is evaluated using results from other meta-analyses and the moderator effects estim ated in the present study. V. Meta-analysis and Public Policy. Meta-analysis is d iscussed as a method for resolving controversial issues. VI. Conclusions. Conclusions and recommendations are gi ven with respect to integrating research, especially with respect to phonics instru ction. VII.I. Introduction to Meta-AnalysisMeta-analysis is a public analysis of research findings. It uses publicly available d ata sources and reveals explicitly to stakeholders how data are selected and analyzed. Private knowledge of data or methodology plays no role. Coo per and Hedges (1994) summarized more elegantly: Two decades ago the actual mechanics of integrating research usually involved covert, intuitive processes taking place in the hea d of the synthesist. Meta-analysis made these processes public and based them on shared, statistical assumptions (however well these assumptions were me t). (p. 11)
7 of 51Nearly a quarter century ago, meta-analysis was dev eloped as a set of statistical procedures for combining the results of many primary studies o n a single topic (Glass, McGaw, & Smith, 1981). Previously, there was no effective wa y to solve the dilemmas of conflicting individual or primary studies. With meta-analysis, each study contributes information in a systematic way, and differences are resolved throug h statistical analysis. In a nutshell, meta-analysis is a method of statist ically summarizing quantitative outcomes across many research studies. Cooper and Hedges (19 94) described this method as consisting of five steps: Problem formulation Researchers decide whether a sufficient number of studies exists for a subject of theoretical (e.g., speed of recall) or practical (e.g., class size) interest. These studies usually investigate treatme nts or interventions in the framework of a comparative research design. (Note 3) For example, we might ask whether students do better in a smaller class (experimental group) rather than a larger class (control group). This step also involves defining a population of interest (e.g., 4th graders) as well as measurements or outcomes (e.g., performance on multi-step math problems). 1. Data collection: Searching the literature Ideally, all relevant studies would be obtained for a meta-analysis. To obtain the most ex haustive sample of studies possible, the researchers must sort through all app ropriate reference systems and publications. Additional studies are frequently add ed by combing through the references of obtained studies as well as databases of unpublished studies. The key idea here is that if a sample of studies is obtaine d, that sample must fairly represent the entire population of studies to avoid bias (in the same way that the U.S. Census must ensure that hard-to-reach subpopulations are f airly represented). 2. Data evaluation: Coding the literature Trained researchers must extract information about each studys results. A standard list of feat ures (e.g., size of the treatment groups) is developed prior to reading through the s tudies, even though some of this information may not be reported in many studies. Di fferent researchers who record study information work with common variable definit ions so that the information is reliable and comparable across studies. (Note 4) The determination of what counts as relevant information for coding purposes should be made by experts who have a thorough understanding of the treatments, populatio ns, and measurements in question. Meta-analysis requires a quantitative measure of ef fect or outcome, but studies using conceptually similar measures often do not use the same nominal instruments or tests. Therefore, to be able to combine quantitative treat ment-control differences across instruments, they must be translated to a common sc ale. For example, if one wanted to add two measurements, one in centimeters and one in inches, it would be necessary to convert inches to centimeters (or vice versa). This is what an effect size (labeled as d ) ideally accomplishes. It is a translation of the me asured effects from different studies into comparable units (in this case, standard devia tions). More description is given in Section V on the effect size measure d but as a rule average effect sizes in instructional research tend to range from 0 to abou t 1. 3. Analysis and interpretation A central question for all comparative studies is the degree to which the experimental group (sometimes c alled the treatment group) outperformed the control group. Once effect sizes a re computed, statistical analyses are used to estimate the average d and its margin of error. Analyses also determine whether certain study features like the duration of treatment influence the effect size. 4.
8 of 51Note that estimation of an effect is a different activity than its interpretation The meaning of a measurement in centimeters can be quit e different depending on, for instance, whether we are talking about the followin g distance of automobiles on a highway or the width of a contact lens.Public presentation At every stage of the meta-analysis, records shou ld be kept regarding procedures. In reporting a meta-analysis, researchers must provide not just statistical results, but also an account of decisio ns that led to those results. In addition, the meta-analysis is not over until the results are linked to the research issues specified in the first step. In short, the findings must be i nterpreted and communicated. They must also be qualified, that is, the researchers he lp readers to understand limitations of the meta-analysis. 5. While the principles of meta-analysis are scientifi c, the methods it employs are not purely formulaic. Human judgment is a key element in each of the five steps. In particular, meta-analysts rely on expert judgment for convertin g narrative descriptions of a studys treatments and subject populations to quantitative measurements. Such coding often requires substantive expertise in addition to research and q uantitative skills. (Note 5) II. Findings of NRP StudyThe subgroup of the NRP for Phonics Instruction des cribed the five steps of its meta-analysis in Chapter 3, Part II of Teaching Children to Read In particular, 11 major conclusions were listed (NRP, p. 2-132 to 2-136). T he report is well-summarized by Ehri et al. (2001, abstract): A quantitative meta-analysis evaluating the effects of systematic phonics instruction compared to unsystematic or no phonics instruction on learning to read was conducted using 66 treatment-control compa risons derived from 38 experiments. The overall effect of phonics instruct ion on reading was moderate, d = 0.41. Effects persisted after instruction ended. Effects were larger when phonics instruction began early ( d = 0.55) than after first grade ( d = 0.27). Phonics benefited decoding, word reading, text comp rehension, and spelling in many readers. Phonics helped low and middle SES rea ders, younger students at risk for reading disability (RD), and older student s with RD, but it did not help low achieving readers that included students with c ognitive limitations. Synthetic phonics and larger-unit systematic phonic s programs produced a similar advantage in reading. Delivering instructio n to small groups and classes was not less effective than tutoring. Systematic ph onics instruction helped children learn to read better than all forms of con trol group instruction, including whole language. In sum, systematic phonic s instruction proved effective and should be implemented as part of lite racy programs to teach beginning reading as well as to prevent and remedia te reading difficulties. For additional detail with regard to the overall re sults, we give the complete text of the first conclusion from the NRP report: Childrens reading was measured at the end of train ing if it lasted less than a year or at the end of the first school year of inst ruction. The mean overall effect size produced by phonics instruction was significan t and moderate in size ( d = 0.44). Findings provided solid support for the conc lusion that systematic phonics instruction makes a more significant contri bution to childrens growth
9 of 51in reading than do alternative programs providing u nsystematic or no phonics instruction. (NRP, 2000b, p. 2-132). Data analyses supporting these conclusions were bas ed on a straightforward design: treatment groups receiving systematic phonics were compared to control groups receiving unsystematic or no phonics instruction. Yet both th e experimental and control groups might receive mixtures of phonics, language instruction, and other activi ties. The NRP did examine whether the effect of phonics instruction w as influenced by moderator variables, such as socio-economic status or phonics programs. However, no attempt was made to classify the degree of phonics or the mixtures of p honics and other language activities in the groups being studied.Treatment and Control Group DefinitionsIn order to understand the overall effect ( d = .41/.44), it is necessary to understand the characteristics of the treatment and control groups (Note 6) The NRP described treatment groups as including systematic phonics instruction while control groups, though they may have had some phonics instruction, as having variou s other types of instruction (NRP, 2000b, p. 2-103) with less systematic phonics. Thus, the effect size generall y signifies the advantage of more versus less systematic phonics instruction: Whereas some groups were true no-phonics controls other groups received some phonics instruction. It may be that, instead o f examining the difference between phonics instruction and no phonics instruct ion, a substantial number of studies actually compared more systematic phonics i nstruction to less phonics instruction. (NRP, 2000b, p. 2-124) Because almost all children received some instructi on in phonics during the course of comparative studies, this formulation is realistic. However, the degree of phonics instruction varied from study to study, and it is possible that a treatment in one study could resemble a control in another.While we believe that the effect size can be a usef ul measure in such situations, it must be realized that any ambiguity in how comparisons vary across studies adds some ambiguity to the interpretation of the overall or average effect size. The NRP surmised that the effect of such treatment-control variability might be to underestimate effect sizes. In many cases, however, children receiving systematic phonics inst ruction were also receiving activities consistent with the aims and purposes of whole lang uage. Thus, uncontrolled mixtures might also serve to overestimate the effects of phonics instruction. Others have written about the false dichotomy betwe en language and phonics instruction (e.g., Fletcher and Lyon, 1998). (Note 7) A number of phonics instruction treatments are described in the NRP report including synthetic, an alytic, analogy, onset-rime, phonics through spelling (NRP, 2000b, p. 2-99), and embedde d phonics. Many contain some degree of language instruction. For example, although emb edded phonics was not defined in the NRP report, Foorman, Francis, Fletcher, Schatschnei der, and Mehta (1998) described their embedded code treatment as including whole-class activities such as shared writing, shared reading, choral or echo reading, and guided reading (p. 40). In addition the teachers would frame a word containing the target spelling pattern during a literacy activity (p. 40). Consequently, the treatment is consistent in some i mportant respects with language-based
10 of 51 instruction, though it can also be described as a t ype of phonics instruction. While such treatments defy simple labels, they can be coded on various dimensions that more accurately describe the package of treatment conditions. Ana lyses can then be undertaken to sort out the unique effects of various instructional activit ies and conditions. Outcome Variables and Units of AnalysisThe NRP subgroup on phonics instruction computed ef fects sizes for dependent variables that fit into one of 7 categories (also see Table 1 ) (Note 8) : Word ID 1. Decoding 2. Spelling 3. Comprehension 4. Nonword reading 5. Oral reading 6. General reading 7. Table 1 Dependent Variable Categories. CategoryLabelNRP Label1decoding regular wordsdecoding2decoding nonwordsnonwords3sight word IDword ID4spellingspelling5comprehensioncomprehension6oral readingoral reading7general readinggeneral reading8language*9phonemic awareness*10alphabetic knowledge*11vocabulary*12writing**Category not used in NRP study For each category within each treatment-control com parison, it is our understanding (NRP, 2000a, p. 1-10) that either mean or median effect s izes were computed for each cohort of students when results for more than one test instru ment were available. In some cases, studies did not report measures for some categories in which case the category was left
11 of 51blank (i.e., a missing value) in Appendix G. At m ost, one effect size was reported for each category for each cohort/comparison.Importantly, measures were excluded from this class ification if they were used during (or as part of) phonics instruction (NRP, 2000b, p. 2-110) Such effect sizes would be expected to be larger due to teaching to the test. No distinc tion was made between standardized and experimenter-devised tests. Because standardized te sts are targeted to a wider range of ability, the NRP surmised that they might be less s ensitive to change and thus underestimate effect sizes slightly (NRP, 2000b, p. 2-111). Criticisms of the NRP Meta-AnalysisThree prominent criticisms of the NRP meta-analysis of phonics instruction have spurred public debate. The first concerns methodology; the second concerns the link between evidence and conclusions; and the third, the proced ures with which research activities were conducted.The first criticism is that a narrow population of children was represented in the 38 studies that comprised the meta-analysis (Garan, 2002). In particular, Garan argued that many of the studies did not include normal readers and none i ncluded groups of advanced readers. Thus, it would be difficult to generalize the findi ngs broadly across typical populations of students. The second criticism is that the term re ading was not used in a consistent manner; the term reading can refer to simple word calling (e.g., a response to the question Can you say this word?), but it can also refer to the ability to derive meaning from connected text (Yatvin, 2002). If it is said that Phonics instruction improves reading, it is important to know what kind of reading is signified The third criticism was that the process used to conduct and report the meta-analysis was fl awed. According to Yatvin (2002), the NRP study on phonics instruction was completed in a very short time. In October, 1999, five months before the due date, a determination was mad e that the completion of the study required resources beyond the capacity of panel mem bers, and it appears that a researcher who was not a member of the NRP was commissioned to conduct the meta-analysis. (Note 9) Upon completion of the study, again due to time co nstraints, the panel originally in charge of designing and conceptualizing the research had o nly four days to review the final report before it went to press. Yatvin also observed that only one panel member (Yatvin) had teaching experience, and thus the NRP had little ex pertise for the purpose of linking research findings to practice.The NRP addressed some of these issues. The 38 stud ies provided 66 (Note 10) treatment-control comparisons, and of these, 23 com parisons included normal readers (about 35%). In regard to the second criticism, the NRP fo und that: The majority (76%) of the effect sizes involved rea ding or spelling single words while 24% involved reading text. The imbalance favo ring single words is not surprising given that the focus of phonics instruct ion is on improving childrens ability to read and spell words. (NRP, 2000b, p. 292) Even from this brief quote, it is clear that a nece ssary distinction must be made between word reading and conceptualizations of reading th at imply understanding of connected text. Word reading is just one connotation of rea ding, yet the distinction isnt maintained consistently in formal documents. For example, in E hri and Stahls (2001) rebuttal to Garan
12 of 51(2001) (Note 11) they reported that clear evidence was found to sup port the conclusion that Systematic phonics instruction was found to be more effective than unsystematic phonics instruction or no phonics inst ruction in helping students learn to read [emphasis added]. (Ehri and Stahl, 2001, p. 18) One could define reading as reads single words in isolation, which would be consistent with the NRPs data analyses. But reading could als o be defined as reads connected text, that is, sentences or stories. Obviously, ones sen se of the studys outcomeas represented in the above quotedepends almost entirely on how r eading is defined. The third criticism was that not enough time was al lotted to carry out the charge of Congress, and that the final report was not subject ed to formal review. In fact, the study was under intense time pressure from inception. Accordi ng to Yatvin, who wrote a minority addendum to the final report, In fairness to the Panel, it must be recognized tha t the charge from Congress was too demanding to be accomplished by a small bod y of unpaid volunteers, working part time, without staff support, over a pe riod of a year and a half. (The time Congress originally allotted was only 6 months .) (Yatvin, 2000, p. 2) Whether the resources and time were sufficient to c arry out such an important study is now a moot issue. The question of interest is whether the meta-analysis conducted by the NRP is sufficiently reliable and valid for guiding instruc tional policy in early reading. In the present study we address the topic of whether the central N RP results can be replicated by a different team of analysts. A successful replicatio n would provide convincing evidence of accuracy and allay concerns about study logistics.III. Reanalysis: Research Questions and MethodsThe NRP results were given for 11 central questions regarding phonics instruction. In this re-analysis, we will be concerned primarily with tw o of these: Does systematic phonics instruction help children to learn to read more eff ectively than nonsystematic phonics instruction or instruction teaching no phonics? (N RP, 2000b, p. 2-132); and Is phonics instruction more effective when it is introduced to students not yet reading, in kindergarten or 1st grade, than when it is introduced in grades above 1st after students have already begun to read? (NRP, 2000b, p. 2-133).Using publicthat is, publishedaccounts of data an d methodology, we re-examined the evidence offered by the NRP on the efficacy of phon ics instruction. We designed an effect size database, recomputed effect sizes for all outc omes available, and then carried out analyses in which effect sizes were related to stud y characteristics. One study by Vickery, Reynolds, and Cochran (1987), which is described in Appendix C, examined the effect of the same treatment on remedial and nonremedial students. Be cause there was no control group, we deleted this study from our database (see inclusion criteria on p. 2-108 to 109 in NRP, 2000b). We included another three studies that were identified by the NRP but not included in their meta-analysis. These are describe d in Appendix A of this report. Thus, our database was constructed from 40 studies originally identified by the NRP; however, the merits of the original NRP sample or sample selecti on process is beyond the scope of the present study. ( Note 12 ; Note 13 )
13 of 51Our analytic strategy had several components. We se lected a unit of analysis, defined alternative weighting schemes, and used multiple re gression to identify the unique contributions of variables that moderate the treatm ent. By moderator variable, we mean a component of treatment delivery that leads to a str onger or weaker effect. Four new moderator variables were constructed for specifying the treatment conditions: the degree of phonics systematicity; degree of coordinated langua ge activities; whether treatments were regular in-class or pullout programs; and whether b asal readers were used. These variables, which were coded from the research studies by means of rubrics, provided the explanatory power missing from the simple comparative design us ed in the NRP analyses. That is, the NRP design did not fully account for variation in t he mixtures and degrees of treatment delivered to both experimental and control groups. Other moderators were borrowed from Appendix G of the NRP report. Using regression anal ysis, we then predicted treatment outcomes (i.e., effect sizes) with the four new mod erators and: the size of the instructional unit (tutoring, small groups, class); whether treat ment conditions were randomly assigned; whether standardized tests were used; and the age (Note 14) of students. There are two important design facets in a meta-ana lysis. The first is a design for data collection while the second parallels the usual sense of the word in the phrase experimental design That is, there is one design for data collection, and another for analysis. In order to address the weaknesses of the simple comparative de sign of the NRP study, we coded moderator variables, but we also planned for a more complete use of the information within each of the 40 studies. In particular, we distingui shed untreated control groups from alternative treatments, and included both, as des cribed below. This can be likened to filling out the cells ofor balancingan experiment al design, while the increasing the number of studies adds to sample size. The recognit ion of this distinction is not evident in the NRP analytic plan.Database DesignIncluding Groups for Comparison As noted above, in each study the NRP designated as the control a group with less systematic phonics than t he treatment group (or groups). Ironically, this procedure in some cases led to ignoring inform ation from groups labeled as control by the authors of the primary studies. For example, in the study by Lovett, Ransby, Hardwick, Johns, and Donaldson (1989) three groups were used: the Decoding Skills Program (DS), the Oral and Written Language Stimulation program ( OWLS), and a Classroom Survival Skills program (CSS). The third group was described as a control procedure in which subjects received the same amount of clinic time an d professional attention as those in the experimental remedial programs (p. 96); however, C SS students received training in activities that didnt include reading. It appears that non-treatment controls such as the CSS group were excluded from the NRP study when program matic controls like OWLS were present. Thus, the NRP effect sizes for Lovett et a l. (1989) are based solely on the comparison of the DS to the OWLS program.In such cases, we computed effect sizes for DS vers us CSS and OWLS versus CSS. However, we coded (with treatment indicators determ ined by rubric codings) the DS program as having systematic phonics instruction wh ile the OWLS program was coded as language-based. This strategy yields an important s ource of information for disentangling treatment effects because untreated control groups can provide a common basis for comparison across studies. The component effects of treatment mixtures may then be more
14 of 51accurately identified.Defining Control Groups. More than one control group may have been available for computing effect size. For example, in Foorman et a l. (1998), there were four groups described as: direct code (DC), embedded code (EC), implicit code-research (IC-R), and implicit code-standard (IC-S). It appears that the NRP analysts used the IC-S group as the control even though the authors of the study assert ed that comparisons among IC-R, DC, and EC provided the most relevant information about ins tructional differences because the IC-R group controlled for teacher training.We decided to use the IC-R group for computing effe ct sizes based on the general rationale in this paragraph, which we used for all studies. T he most valid control was taken as the group that received the same kinds of treatment act ivities (e.g., individual attention, duration of treatment), but not the treatment itselfeither language or phonics. This would serve to control for as many background variables and modera tors as possible. For instance, if there were a choice of control between two groups that di d not involve phonics or language instruction, then we would use this rule to choose the control. We coded systematic language programs as treatments unless there was no t another control group available. In a study with only a phonics group and a language grou p, we compared the phonics to the language group to obtain the effect size, but coded the comparison as being Phonics v. Language rather than Phonics v. Control. At least t hree possible classes of comparison (phonics-control, language-control, and phonics-lan guage) were defined by the rubric indicators.In summary, we included control groups having no sy stematic phonics or language interventions, whereas the NRP analysts did not. Ho wever, when two control groups were available, we chose the one most like the treatment group in terms of characteristics ancillary to the intervention.Coding Rubrics and Inter-Rater ReliabilityWe coded the characteristics of both treatment and control groups with rubric indicators. The rationale for this practice is that coding is a measurement process, requiring inference, and not a simple reading of a study. Since coding i s a measurement process, its scientific warrant should be established by demonstrating inte r-rater agreement. The credibility of the limited moderators coded by the NRP team was also e stablished by demonstrating high inter-rater agreement.In Table 2, the rubrics are given that were used to code treatment characteristics. We distinguished among three levels of phonics instruc tion; two levels of language; basal reader usage; and supplemental/pullout versus regular in-c lass instruction. Rubric codings provide a richer quantitative description of studies in whi ch instruction is comprised of mixtures of phonics, language, and other elements. For each stu dy, three independent codings were obtained. The first codings were given by the autho rs of the present study, each of whom had participated in all aspects of at least one pre vious meta-analysis. None had previously participated in a study of phonics or whole languag e instruction, and none had taken a public position in the phonics versus whole language debat es. The second and third codings were provided, respectively, by an experienced reading t eacher and a university professor, each with a national reputation in reading instruction.
15 of 51 Table 2 Rubrics for Coding Treatment Conditions. PhonicsngNo information in study to infer code.0No specific phonics intervention was given. In mos t cases, we know that it is highly probable that students received some kind of phonics activity, especially for longer interventions. Moreover, even if no phonics instruction was associated with the treatment delivered, it may have been the case that other instructional activities (external to the tre atment) included phonics. In short, we were not able to distinguish among these possibilities. 1Treatment specifically included phonics activities but treatment activities were not described in detail as being direct, syste matic instruction. Organized phonics were embedded in language instruc tion. 2Treatment was described as including direct, syste matic phonics instruction. It was most often the case that this description sp ecifically included blending. ReplacengNo information in study to infer code.0Treatment did not replace regular classroom instru ction. In some cases, the treatment consisted of a supplemental program. For example, students received treatment at facilities outside of schools (e.g., hospital setting on Saturdays). 1Treatment was regular classroom instruction, or th e treatment completely replaced regular classroom instruction. Basa l ngNo information in study to infer code.0Basal reader was not used.1Treatment was described as including a basal reade r, or it was highly probable that a basal reader was used. For example, a 4-year treatment consisting of regular classroom instruction almost certainly used a basal reader at some point, even if it was not specifical ly mentioned. LanguagengNo information in study to infer code.0No systematic or formal language activities were i ncluded. 1Language-based (non-basal) treatment was given. Th is may have consisted of whole word or whole language programs.
16 of 51 For each effect size computation, both experimental and control groups were coded according to the rubrics, allowing for the possibil ity that any group could be coded as having both phonics and language instruction. However, no phonics treatment labeled as such ever had less systematic phonics instruction than the gr oup chosen as the control, though both groups may have had language instruction. In some c ases, study information for coding a rubric was denoted as not given by one or more co ders. Our guiding principle on this matter was that evidence of presence was required in order to make inferences regarding the effects of a rubric variable. We converted not given responses to zeros. For example, if a study did not report that basal readers were used but it was known that the reading program formally included basal readers (and did du ring the timeframe of the study), then assuming their presence was a relatively safe infer ence. However, for less familiar or unknown reading programs, it was safest to assume b asal readers were not used. In short, the conservative approach to coding was to require evid ence of presence rather than absence when linking treatment or moderator indic ators to study outcomes. In Tables 3a-3d, agreement analyses are given for e ach of the four rubric variables separately. Under the column labeled Judges Coding s the number of each possible combination (i.e., unordered triplet) of three code s, one for each judge, is given. Overall, there was substantial agreement among coders, given the evidence-of-presence requirement. In addition to the data in Tables 3a-3d, it is also useful to consider that three raters operating at random with 95 total comparisons would only have an expected value of about 10-11 matches with a 3-point rubric, and only about 23-24 on a 2-point rubric. Table 3a Inter-rater Agreement for the Phonics Rubric (Cronbachs alpha for this rubric was .95) Judges Codings n (95 total)Cumulative PercentAgreement Type 0,0,02223Perfect1,1,11337Perfect2,2,23169Perfect0,0,11282Adjacent0,1,1688Adjacent1,1,2493Adjacent1,2,2598Adjacent0,1,2199unclassed1100 Table 3b Inter-rater Agreement for the Language Rubric (Cronbachs alpha for this rubric was .79.) Codings n (95 total)Cumulative PercentAgreement Type
17 of 51 0,0,05558Perfect1,1,11169Perfect0,0,19790,1,11999unclassed1100 Table 3c Inter-rater Agreement for the Basal Reader Rubric (Cronbachs alpha for this rubric was .82.) Codings n (95 total)Cumulative PercentAgreement Type 0,0,05255Perfect1,1,11874Perfect0,0,119940,1,1599unclassed1100 Table 3d Inter-rater Agreement for the Pullout Rubric (Cronbachs alpha for this rubric was .87.) Codings n (94 total)Cumulative PercentAgreement Type 0,0,03032Perfect1,1,14074Perfect0,0,112870,1,11199unclassed1100 When we encountered a difference among coders, the final code was chosen as the consensus code in almost all cases. In the few case s where a 2-of-3 majority was not obtained, codes were averaged. For example, in one comparison the level of phonics was given codes of 0, 1, and 2, and in this case, the r esults were averaged resulting in a code of 1.0. Given the majority rules principle (Orwin, 1 994), the three judges were overruled 24, 25, and 56 times out of 404 coding instances. This translates into overruled percentages of about 6%, 6%, and 14%, respectively. Thus, an indiv idual judges code was retained in a minimum of 86% of the coding instances. The coeffic ient alphas were relatively high at .95 (degree of phonics), .79 (presence of language acti vities), .82 (use of basal readers), and .87 (regular v. pullout program).The effort in detailing treatment conditions is imp ortant for making a strong statistical link between treatments and outcomes, and would ideally be planned in the design of the study
18 of 51and coding protocol. Even so, a dose of realism is required in this effort. The typical study examined lacked clarity with regard to treatment co nditions. It was not uncommon that a total of three or four sentences were devoted to de scribing an intervention. Though we feel 69% is an acceptable rate of perfect agreement for level of phonics instruction (with a reliability of = .95, see Table 3a), at least part of the 31% of disagreement can be attributed to the lack of clear descriptions of independent va riables. Some measurement error reflects ambiguous descriptions rather than ambigui ty inherent in the judgment process. In the analyses reported below we used, but did not code, other moderator variables in addition to the rubric indicators. These moderators were borrowed directly from the NRP study including treatment unit, age/grade, SES, and reading ability. We coded, but did not obtain inter-rater agreements, for several addition al variables for each effect size in our database including the size ( n ) of each treatment/comparison group, whether the e ffect size was from a randomized study, and whether the effect size was from a standardized instrument.Dependent VariablesVariable Categories All effect sizes were recomputed for all availabl e outcome measures that could be considered as falling into one of the categories in Table 1. In some cases, we considered outcomes that the NRP did not use, such as alphabetic knowledge, which refers to how well students can connect phonemes to graphe mes. Though these measures fell outside the range of the NRPs definition of readin g, we felt the information was useful. Effect Size Computation Most criticisms and counter-criticisms of the NRP report accept as their starting point the computed effect sizes as o btained by the NRP analysts. We did not use the published NRP effect sizes because independ ent computation is more consistent with the goals of a validation study based on the m erits of replication. Therefore, one major focus of the present study is computational: Can th e general effect size obtained by the NRP analysts be replicated? However, since we recompute d effect sizes based on a different design (than the one used by the NRP) for experimen tal-control comparisons, a one-to-one comparison was not possible. For this purpose, we d evised an approximate method of comparison (described in Section IV).Computing an effect size can pose a difficulty with which meta-analysts are all too familiar, but one that may not be transparent to a consumer o f meta-analytic information. In studies that do not report the necessary information for a simple computation, information must be pieced togethersometimes using specially designed procedures that may require a number of assumptions. In this section we review a number of these issues that are pertinent to the studies on phonics instruction. Although the DSTAT program was used for computations (Johnson, 1989) by the NRP team, it is often the ca se that judgments must be made as to what information to enter into the program; differe nt choices may yield different results even when calculations are error-free. In a number of in stances, the NRP team may not have appreciated the complexities of computing the effec t size d or they did not provide rationales for their methods. In this regard, we pr ovide several clarifications below for facilitating accurate effect size computation.Although the NRP cites Cooper and Hedges (1994) reg arding formulas for computing effect sizes, the basic formula given by the NRP (NRP, 200 0a, p. 1-10) and reproduced below is incorrect:
19 of 51(1) Compared to the pooled effect size estimator ( g ) given by Hedges (1985, p. 78) (2) we can see that while the numerators of (1) and (2) are the same, the denominators differ (vTand vC are the degrees of freedom for the experimental an d control groups, respectively). Moreover, it can be shown that the effect size give n by (1) is always larger than that given by the standard formula in (2). The magnitude of th is difference is not large, however, and the NRP calculations appear to have been performed with the correct formula. Nevertheless, it is important to communicate established procedur es in a public document. If a nonstandard formula is used, a justification should appear in text, but we know of no justification for the formula in (1). (Note 15) For the most part, we computed effect sizes in a ma nner consistent with general methodological descriptions given in the NRP; the H edges correction was used in all cases (Hedges & Olkin, 1985, p. 81). However, because few in-depth details were provided (e.g., NRP 2000b, pp. 2-110 to 2-111), we used several add itional guidelines for the current study: a) Standard deviations were pooled across all postt est treatment and control groups within a cohort of students to create a comm on denominator. Hedges effect size adjustment was applied to g to arrive at d (using degrees of freedom based on the pooled sample).b) When pretest means were available, effect size n umerators were computed as differential average gains to help control for preexisting differences. Effect sizes, according to the first guideline, were then obtained via division with a common posttest standard deviation. If covariance a djusted effects were reported, these were used in the numerator instead of the difference between average gains of treatment and control groups.c) When testing was carried out on more than two oc casions during a treatment intervention, we computed gains based on pretest an d immediate posttest means. If a treatment spanned several years (or gra des), we computed an effect size for the first year using the second guideline. For each ensuing year separately, we computed an effect size using the pr evious years posttest as the following years pretest.d) Effect sizes were computed with custom programmi ng developed for each individual study rather than using one of the avail able software products. For the most part, calculations were based on formulae given by Cooper and Hedges (1994). Units of Analysis In some cases, classrooms or even schools are use d as the units of analysis
20 of 51rather than individual students, and this phenomeno n did occur in the set of phonics instruction studies. In this case, classes (or scho ols) are the units of observation, and class means comprise the data to be analyzed. The formula given in (2) typically pools individual level standard deviations that are first calculated with the formula: (3) When individual observations are group means, howev er, the estimate of variability, s' is (4) which is the formula for the standard error of the mean. Upon comparison, it can be seen that (4) will be smaller than (3) depending on n which is the class (or school) size. Therefore, an effect size using class means will be larger than one based on individual student scores by the multiplicative factor n. With moderately sized classes, the use of means can result in substantially larger effect siz es, but these are not comparable to the effect sizes of other studies whose units of observ ation are students. To remedy this disparity, effect sizes must be translated to the i ndividual metric. (Note 16) As we shall see below, the greatest discrepancy (between a recomput ed and original NRP effect size) was due to a unit of analysis problem.Weighting StudiesIn the NRP study, effect sizes were computed for ea ch experimental treatment. For example, if there were one outcome variable, two distinct ph onics-based treatments (A and B), and one control group (C), two effect sizes would be co mputed (A versus C, and B versus C). If there were two or more outcome variables in a depen dent variable category (e.g., two spelling tests), the effect sizes for A-C and B-C w ould be averaged separately within this category.Because the NRP reported 66 comparisons from 38 stu dies, some studies contributed more than one effect size. For example, one study by Vic kery et al., 1987, contributed 8 comparisons4 grade level cohorts crossed with two levels of remediation. There are a number of methods for computing the overall average d in this situation. First, one could compute the simple average across the 66 comparison s given in Appendix G of the NRP report (NRP, 2000b, pp. 2-169 to 2-175), which resu lts in a mean of .46. This is close to the value .41 which was reported by Ehri, Nunes, Stahl, and Willows (2001). Implicit in this procedure is that the Vickery et al. (1987) study r eceives 8 times the weight of a study that contributed a single effect sizebecause it examine d 8 distinct treatment-control cohorts. (Note 17) A second method consists of weighting studies by th e total n of the comparison (treatment + control); in other words, comparisons with larger n s would receive more weight. This was the method used by the NRP, and results in mean d = .41. In the NRP study, the rationale was given that
21 of 51 The subgroups [committees] weighted effect sizes by numbers of subjects in the study of comparison to prevent small studies from o verwhelming the effects evident in large studies. (NRP, 2000a, p. 1-10). With this practice, however, large studies overwhel m small studies. For example, in Gersten, Darch and Gleason (1988), data from 1973-1 974 are available for two cohorts of children with a total n = 242. Treatments were provided at the class level In contrast, one comparison described by Gillon and Dodd (1997) cont ains n = 10 students in two groups. Given a simple weighting by n the latter study would have about 1/24th the weig ht of the former study. It is our opinion, that this weightin g practice should not be automatic; application of statistical weights necessarily give s studies using classes more weight than studies using small groups or tutoring.In a third method for averaging across studies, sep arate studies are given equal weight. In this case, the 8 effect sizes in Vickery et al. (19 87) would each receive a weight of 1/8; and the weights would sum to 1.0. This weighting practi ce would be repeated for all studies resulting in a set of weights that would sum to exa ctly the number of independent studies. In the NRP study, this weighting procedure results in an mean d = .54. (We note that this effect is larger than the estimate reported in Teaching Children to Read but stay tuned.) In our opinion, this approach makes sense when a set of ef fect sizes is relatively homogenous. Though Shadish and Haddock (1994) asserted that al l things being equal, weighting sample size is the most widely accepted practice, H edges and Olkin (1985) cautioned that statistical weights should be considered only in ca ses with homogenous effects sizes: Before pooling estimates of effect size for a serie s of k studies, it is important to determine whether the studies can reasonably be des cribed as sharing a common effect size. (p. 122) Thus, all things being equal can be accurately in terpreted as sharing a common effect size.A fourth method of weighting represents a compromis e between statistically weighting and equally weighting studies. Let the statistical weig hts be labeled as WGT1 and let the equal representation weights be labeled WGT2 A compromise between the two weight types can be achieved by taking WGT3 = WGT1 WGT2 In the latter approach, consideration is given both to study representation and sample size. See T able 4 for definitions of the three types of weighting. For the analyses in the present report, we examine regression estimates derived from the weighting systems represented by WGT1 and WGT3 Table 4 Definitions of Alternative Unit Weights: Equal Representation, Optimum, and Compromise. WGT1:If a single study contributed k records to the aggregated database, the equal representation weight was defined as:
22 of 51 WGT2:For a particular record in the aggregate datab ase, the total number of observations for the treatment and control groups w as: The weight was then taken as Rather than using this approach, we opted to use the optimum weight defined by Hedges and Olkin (1985, pp. 86 & 110) as: After examining the distribution of WGT2 we set a maximum value so that the highest values were no more than 15 times large r than the smallest values. WGT3:Given WGT1 and WGT2 this compromise weight WGT3 was computed as: How studies should be weighted is a critically impo rtant issue, because different weighting methods may give different results. Ironically, the NRP choice resulted in large studies effects overwhelming those of smaller studies, and the consequences of using this choice should be carefully considered. In our database of effect sizes, the test of homogeneity was highly significant ( Q = 813.46, 223 df; equivalent z -statistic is roughly z = 27.94) indicating that the studies did not share a common effect size (i.e., the hypothesis o f homogeneity was rejected). Statistical weights may be inappropriate for the NRP data because of potential qualitative differences between small and large stu dies. Moreover, some studies included multiple comparisons, and statistical weighting giv es such studies many times the influence of studies with a single comparison. A procedure in which studies are given equal weight may provide the most equitable reading of the exp erimental literature, but a compromise, which balances representation and statistical preci sion, may also be useful. Other procedures may also be defensible, but in any case an explicit justification should be provided. The issue of weighting involves notions that are fu ndamental to the ideals of meta-analysis. Though it can be understood as a statistical issue, weighting can also be understood relative to the questions What counts as evidence? and Ho w should evidence be accumulated? What counts as research in education usually comes in the form of a study in which an author analyzes data and reports conclusions based on those analyses. The results from a single study may be extremely trustworthy and valua ble, and so a problem arises when we wish to sum the evidence in two or more studies. Other things being equal, conclusions from two studies using the same data would not be v alued equally to conclusions from two independent studies. Yet the problem is not simply to determine appropriate weights for different studies, but how to understand the role o f cumulative evidence vis--vis the role of in-depth knowledge flowing from a single, well-exec uted study. Meta-analysis is a systematic method for summarizin g the knowledge inherent in a research literature. Information concerning study outcomes b ased on unreported or private knowledge can obviously not add to this summary, even though what is actually learned from a study
23 of 51does include unreported and private knowledge. The trut h of analytic conclusions can only be linked to reports of empirical investigations. This assertion is very different from the garbage ingarbage out axiom, which implies that a simple truth intruth out model is possible for synthesizing research studies. The pro cess of establishing warrants for conclusions is different in meta-analysis than it i s in primary research since in published primary studies authors have direct access to conte xtual information (e.g., vested interests) that is not printed, but nonetheless influences rep orted conclusions. One important assumption of meta-analysis is that the effects of unreported information will average out across independent studies. This is why fair repres entation and appropriate weighting strategies are such important prerequisites to vali d conclusions. Case StudiesThe quality of any meta-analysis is fundamentally b ased on studies that meet inclusion criteria. In the NRP phonics instruction meta-analy sis, the foremost criterion was that Studies had to adopt an experimental or quasi-expe rimental design with a control group. (NRP, 2000a, p. 2-108). In addition studies had to appear in a refereed journal after 1970, had to provide information for testing the efficacy of phonics instruction on reading, and had to report statistics necessary for computing effect sizes. Having obtained such studies, information was coded and analyses were conducted. The goal of the NRP meta-analysis was to identify reliable and replicable results in the area of early reading. In Appendix B, we provide a perspective on three st udies that met these inclusion criteria. Our goal is to provide readers with a deeper famili arity with the literature, one that extends beyond the typical boundaries of a meta-analysis. T his is important for illustrating how well the inclusion criteria performed in obtaining metho dologically rigorous studies, and for giving a more salient notion of the confidence with which we can generalize. Indeed, cases studies were also included in the NRP report becaus e of their descriptive value. We emphasize that the studies in Appendix B of the pre sent report are given for the purpose of illustrationissues arise with any study put under a microscope. The case studies serve to illustrate methodological issues in a number of areas including: choice of control group, unit of analysis, and stud y selection criteria. While all three studies use quasi-experimental designs, a more in-depth exa mination of these can facilitate a practical understanding of the variety and limitati ons in this design approach to reading research. In our judgment, these studies are repres entative of, if not of higher quality than, the entire set of 40 studies.IV. Re-Analysis: ResultsThe NRP used cohort comparisons as the unit of anal ysis, and then applied statistical weights. (Note 18) We used two strategies for weighting. (Note 19) The first strategy is the meta-analytic equivalent of one person one vote r epresentation. In the second compromise strategy, we combined statistical (inverse variance or comparison n ) weights with equal representation weights. We remind the reader that t he usefulness of weightingas well as that of the entire meta-analytic enterprisedepends on how well a set of studies represents the research literature.The process of coding resulted in obtaining 491 eff ect sizes from 40 studies for 12 dependent variable (DV) categories. The Vickery stu dy (described in Appendix C) was deleted due to lack of a control group. This left 3 7 original NRP studies, to which we added
24 of 51three studies with phonemic awareness outcomes. It appeared to us that the latter three studies (described in Appendix A), which were ident ified but not included in the NRP analysis, met the inclusion criteria of the NRP. Ea ch of these studies, which contributed 7 records total to the database, included at least on e reading outcome from categories 1-6 in Table 1. This database did not include effect sizes from follow-up comparisons. The data file contained one data record for each effect size However, single studies often contributed more than one effect size for a DV category. Moreov er, a d for the same outcome variable category might be computed for more than one cohort within a study. To manage this redundancy, we aggregated effect sizes to the compa rison level within each DV category within a study. This resulted in a primary analysis file of 225 observations (out of a possible 480, which equals 40 studies multiplied by 12 DV ca tegories); 60 of these represented DV categories not included in the NRP study. For each case in the aggregated file we included moderator variables such as duration of treatment, size of the treatment unit, rubric codes, and the like.Our unit of analysis was comparison. That is, if a study compared one treatment to one control group, and measured two outcomes, then ther e were 2 effect size records for one comparison. In some cases, a study had two treatmen t groups (T1 and T2) and one control group (C); in this case with two outcomes, there we re 4 effect size records (T1 v. C, and T2v. C. crossed with two outcomes). Equal representat ion weights were then obtained as the inverse of the number of records per study. Multipl e cohorts were averaged, if they existed, within comparison unless the treatment conditions c hanged across time. Agreement with the NRP StudyBecause of the design difference between the NRP me ta-analysis and the present reanalysis, it is not possible to compare the effect sizes for the two studies directly. However, if effect sizes are aggregated to the study level (excluding studies with TP = 0), we can examine the consistency of the two sets of effect sizes. In Fig ure 1, the scatter plot shows that two studies (labeled 12 and 53) appear as outliers. Study 53 co ntained an ( d = 8.79) outlier and appeared to have been removed from most, if not all, NRP cal culations. In study 12, effect sizes were computed by the NRP team with class means; the requ ired conversion of the pooled standard deviation to the individual metric was not made. With these two studies removed, r2 = .754 for effect sizes based on the original 7 NR P categories (e.g., Nonwords, Decoding, etc.) with TP=1 or TP=2.
25 of 51 Figure 1. Scatterplot of NRP Calculated Effect Size s and Our Re-Analysis Calculated Effect Sizes Again with studies 12 and 53 removed (as well as Vi ckery et al., 1987), the overall averages of these two sets of effect sizes do not significan tly differ using a paired samples t-test (t = -.447, p = .658, 33 df). Clearly, the same general information for effect size was obtained, though a higher level of agreement (correlation) wo uld be desirable. We did not have the disaggregated NRP effect sizes, that is, Appendix G reports effect sizes aggregated by the outcomes classification. For the most part, it was not possible to compare specific effect sizes directly.Level of Phonics InstructionWe computed the overall average d in a different way than the NRP analysts who first computed an average for each cohort, and then compu ted a weighted average of these (i.e., the cohort averages) across studies. We obtained av erages directly from our database, using equal study representation and compromise weigh ting. The analysis of central interest is the difference between systematic and less systemat ic phonics, since the latter is what many, if not most, students already receive. We used the TP rubric variable (scale 02) to describe the level of phonics as a break variable for comput ing the weighted means given in Table 5. The group labeled None/not given in Table 5 (TP = 0) contains treatments that were included as alternatives to systematic phonics, inc luding language-based approaches. These treatments were either not coded by the NRP analyst s, or they were used as controls. In the present study, these were coded as treatments if a separate untreated group was available as a control. In other words, our treatments consist o f both phonics and language-based interventions. Table 5 Breakdown of Effect Sizes by Type of Phonics Delive red in the Treatment Group* Outcome Set
26 of 51 *Note: Both the compromise ( WGT3 ) and equal representation ( WGT1 ) outcomes sets are given with sums of weights rather than n However, for the WGT1 set the sums of weights are equivalent to the number of studies. All depend ent variable categories are included. A first approximation of the efficacy of systematic phonics is thus given in Table 5 as the difference between systematic (TP = 2) and less sys tematic (TP = 1) phonics for which we obtained d = .514 .243 = .27, using WGT1 This is about 30% smaller than the magnitude of the effect reported by the NRP. Table 5 also con tains results for WGT2 ; however, the results are similar for both sets of outcomes. In t he next section, we adjust this effect for other moderators that are correlated with the treat ment variable. Moderator AnalysisAs noted above, we created some moderators and borr owed others from the NRP study Appendix G. We examined the 15 moderators below, re cognizing that a single outcome could have multiple influences. For this reason, we used weighted multiple regression analysis to sort out the unique contributions of mo derators in predicting effects sizes. In this analysis, we examined two sets of moderators: Set IVariable NameSet IIVariable NameExperimental PhonicsTPTutoringTutorLanguageTLDurationMonthsBasalTBStandardized TestStandardReplacementTRTrue ExperimentRandom Control Grade Grade PhonicsCPNormal v. At Risk/LDNormalLanguageCLExpanded v. NRP DV categoriesTagBasalCB ReplacementCR Set I contains the treatment moderators based on th e rubric codings of each comparison group. Set II contains other aspects of treatment i ncluding tutoring (yes or no); treatment duration; whether the instrument was standardized; whether the experiment was randomized (yes or no); grade; reader ability category; and wh ether the outcome fell into one of the original 7 NRP categories (yes or no).We conducted the regression analyses with two ortho gonal contrasts for degree of phonics instruction, because effect sizes may not be linear across the categories of TP as suggested in Table 5. The contrasts TP1 and TP2 were coded as: TP1: TP1 = 2/3ifTP = 0 No Phonics or Unknown
27 of 51 TP1 = -1/3ifTP = 1, 2 Some or Systematic Phonics TP2: TP2 = 0ifTP = 0 No Phonics or Unknown TP2 = -.5ifTP = 1 Some Phonics TP2 = .5ifTP = 2 Systematic Phonics According to this coding, TP1 represents the differ ence between treatments coded as having no phonics or unknown, on the one hand, and treatme nts coded as having at least some phonics, on the other. The contrast TP2 represents the specific difference between treatments coded as having some phonics, and treatm ents having systematic phonics. In the regression analyses below, we first entered into the equation the degree of treatment phonics (TP1 and TP2). We then entered the rest of the 14 (7 Set I + 7 Set II) variables into the regression using a forward stepwise procedure. (Note 20) We viewed this as a kind of natural competition of the variables in explaining the results, especially because we took an agnostic stance with respect to reading theory and the previous NRP results. Results for two separate regressions are reported below. In Table 6 regression coefficients are given for the WGT1 weighting method, and in Table 7 for the WGT3 weighting method. Table 6 Regression Coefficients for the Analysis Weighted b y WGT 1, with R2=.322 Table 7 Regression Coefficients for the Analysis Weighted b y WGT 3, with R2=.199
28 of 51For the WGT1 outcome analysis, the effect of TP1 was d = -.067. This means that treatments using no phonics or an unknown degree of phonics ha d less of an effect than programs that did use a measurable amount of phonics. As shown in Table 6, programs using systematic phonics instruction outperformed programs using les s systematic phonics with d = .241. The systematic phonics effect, however, is smaller than the effect for individual tutoring ( d = .399). In addition, standardized tests tended to gi ve larger effects ( d = .186); studies in which control groups used language approaches had lower e ffect sizes ( d = .320); and treatments that used language approaches had larger effect siz es ( d = .257). Results for WGT3 analysis are given in Table 7. The results are similar to th ose in Table 6 with the effect for systematic phonics given as d = .188; the tutoring effect was moderately smaller ( d = .290); and the language effects were roughly similar for CL ( d = -.221) and TL ( d = .228). (Note 21) Neither analysis provided evidence that randomized experiments give different results than quasi-experimental studies, or that the results dif fered for the NRP and the expanded set of outcomes categories.The result for tutoring requires some discussion si nce it appears inconsistent with the NRP results. The unweighted effect of tutoring d = 1.09 is reported in Ehri et al. (2001, Table 2), while the effects for small group and class instruc tion are given as .44 and .37, respectively. Thus, the unweighted tutoring effect was documented by the NRP. When studies were weighted by size, Ehri et al. (2001, Table 1) the e ffect sizes for tutoring, small group, and class instruction were .57, .43, and .39, respectiv ely. This change in NRP estimates results from the weighting scheme used, but also from the d eletion of the study by Tunmer and Hoover (1993). (Note 22) In the present analysis, the deletion of this stud y results in a tutoring estimate of d = .21 ( p < .007) while the phonics estimate is virtually un changed. The Tunmer and Hoover (1993) study also illustrates an important issue for interpreting the regression results. Recall that there were two trea tment groups, and one untreated control group. The first treatment was the Standard Reading Recovery (SRR). It was modified by one and only one change: a systematic phonics compo nent was added. This modified treatment was then given to the second experimental group (MRR). We coded the first group (SRR) as TP = 1 and the second (MRR) as TP = 2, rec ognizing the difference between the two as the best estimate of the systematic phonics effect. This is what the contrast TP2 represents. The difference between the untreated co ntrol group and the phonics groups (SRR and MRR) is the effect estimated by the first contr ast TP1. We examined residuals for the weighted regression a nalysis and found evidence of one outlier (standardized residual |z| > 4.5). This cas e was removed; however, this decision had very little effect on the model estimates.Differences Between Outcome CategoriesWe did not explicitly examine outcomes for dependen t variable categories because there were relatively few studies that contributed to any particular category. Our primary goal was to replicate results on the overall efficacy of pho nics instruction. However, we did examine residuals from the weighted regression model and te st for residual differences between the DV categories given in Table 1. Using an unweighted analysis (to increase n ) and comparison as the unit of analysis, we found no sig nificant differences, F(11, 212) = .805, p = .635. This implies that there were no differentia l effects by DV category. In particular, the average residual for Spelling was virtually zero. W e do not think this result implies that
29 of 51phonics instruction is equally effective for all de pendent variable categories, but rather that fine-grain discriminations between different types of reading outcomes require more precise data than were obtained from the phonics instructio n studies. Effects by Grade, Unit of Instruction, and DurationWe had a special interest in examining variation in effect size by grade/age. This scatter plot is given in Figure 2, in which it can be seen that in early grades systematic phonics instruction outperforms typical phonics or no/unkno wn phonics instruction. However, differences among these categories are small shortl y after grade 3. A conservative reading of this evidence would indicate that there is no evide nce that systematic phonics instruction outperforms alternative treatments after grade 3. H owever, the phonics indicator is confounded with other treatment variables in the ea rly grades, and the strongest inferences about the efficacy of phonics instruction are obtai ned from the regression analyses. It should be kept in mind that the trends represent changes i n phonics outcomes rather than changes in reading comprehension. The outcomes in Figure 2 app ear to have an upward trend beginning just after grade 3. However, the existence of this trend was not verified in the regression analyses using a quadratic term for grade/age. Thus the information in Figure 2 should be interpreted with some caution. Figure 2. Effect size plotted by grade and degree o f phonics instruction. (On the horizontal axis, the point 0 (zero) represe nts kindergarten.) We also plotted tutoring versus other treatment uni ts (i.e., small group and class) in Figure 3. Here it can be seen that tutoring outperforms ot her instructional unit sizes across the approximate range of kindergarten to fifth grade. F urthermore, there is a suggestion, that tutoring has a greater effect in kindergarten and f irst grade, but also begins to increase again
30 of 51after third grade. Figure 3. Effect sizes plotted by grade and unit of instruction. (On the horizontal axis, the point 0 (zero) represe nts kindergarten.) In Figure 4 effect size is plotted against the dura tion of treatment in months. Again the effects of tutoring are superior to those of other units of instruction, but here the effects peak at about 4 months and decline thereafter. We note t hat duration here denotes the chronological length of treatment and does not indi cate intensity (e.g., minutes per day).
31 of 51 Table 8 Average Effect Sizes for Instructional Methods Given by Hattie (1999) Teaching methods d n of d s Direct instruction.82253 Figure 4. Effect sizes plotted by duration of treat ment in months and unit of instruction. V. Re-analysis: DiscussionCohen (1988) is commonly cited as suggesting that a n effect size of .2 is small, .5 is moderate, and .8 or above is large. However, the pr imary criterion for judging an effect size in educational research is its potential value for informing or benefiting educational practice. Small effect sizes can be valuable, and likewise la rge effect sizes can be trivial depending on the treatment and outcome in question. McCartney an d Rosenthal (2000) wrote, "There are no easy conventions for determining practical impor tance. Just as children are best understood in context, so are effect sizes" (p. 175 ). Average effect sizes only provide information about whether a program works in a gene ral sense. A more useful question is under what circumstances do programs work best? (M cCartney and Dearing, 2002). To discover these circumstances requires that program characteristics be coded and related to effect sizes. An average effect size can also be ev aluated with respect to other kinds of educational treatments. While this information does not provide a definitive rule, it does allow readers to make up their own minds about the practical significance. In the present reanalysis, the estimated effect size for systematic phonics was d = .241/.188 (for WGT1 and WGT3 ). This can be compared to effect sizes reported byHattie (1999, Table 7) for variousinstructional methods (See Table 8). The overall average is about .4. In
32 of 51 Remediation/feedback.65146Class environment.56921Peer tutoring.50125Mastery learning.50104Homework.43110Teacher Style.42*Questioning.41134Advance organisers.37387Simulation & games.34111Computer-assisted instruction.31566Instructional media.304421Testing.301817Programmed instruction.18220Audio-visual aids.166060Individualisation.14630Behavioural objectives.12111Team teaching.0641* Not given. addition, Lipsey and Wilson (1993) examined 302 meta-analyses of avariety of psychological, educational, and behavioralinterventions. Interestingly, they also found that the averagetreatment effect (averaging across meta-analyses) for high qualitystudies was .4. The largest d s in the present study were for tutoring(.399/.290); and use of languageactivities (about .288/.224). In this context, we would conclude that theadvantage of systematic phonics instruction over some phonicsinstruction is significant, but cannot be clearly prioritized over otherinfluences on reading skills. Theregression model suggests, furthermore, that the effects ofphonics, tutoring and language activities are additive It could be argued that the systematic phonics effect is actuallylarger than the estimate d = .241, and so the magnitude of the NRPestimate (about .4) is not anunreasonable expectation. However, the studies examined in thismeta-analysis typically did not accurately describe the degree of phonics in the control groups. Thus, while the expe ctation of d = .4 may be plausible, it is not supported by the data. The effect size d = -.067 ( p > .05) for present v. absent/unknown phonics instruction provides a cryptic message rega rding alternative approaches to reading instruction. This effect is difficult to interpret because it depends on the unknown components of instruction. In the current study, w e did not analyze this effect further. However, for teachers who currently teach some phon ics, the expected benefit from a shift to systematic phonics is d = .241/.188. The present reanalysis suggests that tutoring and language activities are at least as effective in pr omoting phonics-oriented reading as systematic phonics instruction. (Note 23) Interpretation of the Evidence on Phonics Instructi on The NRP subgroup on phonics instruction concluded t hat Findings provided solid support for the conclusion that systematic phonics instruction makes a more significant contribution t o childrens growth in reading than do alternative programs providing unsy stematic or no phonics instruction. (NRP, 2000b, p. 2-132)
33 of 51Based on our reanalysis, the evidence provides ambi guous support for this conclusion. Systematic phonics instruction did outperform treat ment conditions in which a more typical or moderate level of phonics instruction was provid ed. But we identified tutoring and language as critical elements of a reading program in addition to phonics. The data suggest that a reading effect size has the potential to triple when these elements are added to systematic phonics instruction. This balance of com ponents is critical in the early grades because the data suggest that after about third gra de phonics instruction may be less effective. (Note 24) This is more-or-less consistent with the NRP findi ng that systematic phonics instruction is most effective in the earlie r grades (NRP, 2000b, p. 2-133). The moderator most strongly related to outcome is t he unit of instruction. Tutoring showed a strong effect throughout grades 1-6 (little data ar e available to extrapolate further). Though shorter phonics programs tended to have larger effe cts, tutoring was also more effective in this instance. In programs of longer duration, the advantage of tutoring dissipated. Regarding research methodology, we found that standardized in struments (which were published and/or normed) tended to show larger effects, contr ary to the expectations of the NRP analysts. This finding, however, was not consistent across the two approaches to weighting ( WGT1 and WGT3 ). Finally, the regression results we obtained with tw o different approaches to weighting were roughly similar, but the deletion of one case did m ake a noticeable impact on the estimated effect for tutoring. This is, unfortunately, the re sult of a relatively small sample for conducting analyses. In this situation, there is no t a single correct model for obtaining estimates, but this is not sufficient reason for ig noring the complexities of the data set. Ultimately, this problem should be resolved by exam ining larger samples of studies.VI. Meta-analysis and Public PolicyIn the first application of meta-analysis to resear ch on the effectiveness of psychotherapy (Glass et al., 1981), the researchers confronted is sues about research integration: how to define the population of studies to be synthesized (only published studies, only studies that met a priori standards of rigor?); how to select an d measure the aspects of a study to be related to the outcomes of that study; how to class ify studies and calculate their effect sizes when the primary researchers failed to report compl ete evidence; and how to synthesize outcomes when studies report results for varying se ts of outcome measures. (Note 25) The resolutions of such questions and issues worked the ir way into the development of meta-analysis as a methodology that helps social sc ientists to distill and validate conclusions from a diverse research literature. This accumulati on of research findings is not only helpful for settling disputes among researchers, but has be come an important method for designing evidence-based public policies.Meta-analysis would appear to offer great potential for objectivity and even-handedness in the synthesis of research. Prior to the 1970s, rese arch synthesis had been fraught with biasthe reviewer selected studies that favored one perspective and cast others out, typically for ad hoc reasons. Because of its balanced approach, meta-an alyses might resolve polarizing conflicts by making the fullest use of t he research literature. The recent report from the National Reading Panel was likewise motiva ted in part by the desire to use the best evidence available to guide instruction in reading. Ironically, this effort has stimulated controversy regarding what constitutes evidence as well as sound research procedures.
34 of 51Meta-analysis is a kind of quality control mechanis m in the process of making sense of numerous individual studies. Yet criteria for the v alidity of a meta-analysis itself must also be considered. Is there is a general schema for pro ducing meta-analyses that encourages the application of new knowledge? In recent years, it h as become evident that a more systematic approach to meta-analysis is required in order for its original ideals to be attained. In the sections below, we explore issues of scientific due process that appear necessary for producing high quality meta-analyses, especially in areas of research laden with diverse philosophies. Included in this discussion are proce dural standards, assembly of expert panels, and peer review.Standards for Meta-AnalysisThe NRP was directed to employ rigorous research m ethodological standards in carrying out its charge. However, the NRP report included a total of 7 pages (NRP, 2000a, p. 1-5 to p. 1-11) specifically addressing methodological iss ues (the seventh page in this section consisted of 2 references). Issues particular to ph onics instruction were covered in an additional 5 pages (NRP, 2000b, p. 2-107 to p. 2-11 1). Altogether, less than one page is devoted to data analysis, and this contains one inc orrect formulaa reference to the software used to compute the effects sizes is provi ded (which presumably used the correct formula). An ensuing report of the results by Ehri, Nunes, Stahl and Willows (2001) devoted just over 1 page to methodological issues beyond st udy selection. Perhaps this lack of attention to analytic issues was because the NRP in terpreted rigorous standards to mean rigorous selection criteria for including studies but the results of a meta-analysis depend as much on the rigor of the analytic procedures.We think it is important for policy-oriented meta-a nalyses to be designed in advance with clear descriptions of basic analytic strategies. Fo r example, the Campbell Collaborative suggests that researchers provide a rationale for w hy a particular effect size metric was chosen; under what conditions an effect size will b e adjusted for bias; how missing data will be handled; and so forth. The Campbell Collaborativ e has been working on a broader set of criteria for meta-analysis that will play an increa singly important role in establishing the authoritativeness of a research synthesis. (Note 26) Constituting Panels and Expert ReviewBeyond the Campbell Collaborative principles, there would seem to be an important role of due process in selecting committees to guide meta-a nalyses, especially for meta-analyses that have great potential for influencing teaching practice. The Congressional bills that directed establishment of the National Reading Pane l (SB 939, HR 2192) required that The Secretary of Education, or the Secretary's desi gnee, and the Director of the National Institute of Child Health and Human Develo pment, or the Director's designee, jointly shall establish a National Panel on Early Reading Research and Effective Reading Instruction. (3:13-18) However, the legislation itself provided only two s entences to guide selection of panel members: The panel shall be composed of 15 individuals, who are not officers or
35 of 51employees of the Federal Government. The panel shal l include leading scientists in reading research, representatives of colleges of education, reading teachers, educational administrators, and parents. (4:4-9) Contrast this with the selection guidelines of the Institute of Medicine (IOM), which is an institutional constituent of the National Academies of Science: Committees are the deliberating and authoring bodie s for IOM reports, although strict institutional processes must be followed and the peer review process is independent of the committee. Most committees are c onsensus committees, meaning the process is designed to reach consensus on the evidence base and its implications. Where the published data are insuffic ient to support a conclusion, the committee may use its collective knowledge to a rgue for conclusions. The committee is formed by identifying the expertise an d perspectives necessary to address the study topic, soliciting and receiving n ominations for candidates from a wide and extensive number of sources, presen ting a proposed slate and alternatives to the IOM leadership group, receiving approval from the IOM President, and formally requesting appointment from the NRC chairman. A process of seeking to identify biases and potential conflicts of interest takes place and may disqualify individuals. (Note 27) The NICHD and Secretary of Education appear to have conducted a selection process consistent with the IOM guidelines in constituting the NRP (Note 28) ; however, there is no detailed description of the procedure used to choos e panelists from about 300 nominees. Visible selection procedures are important for esta blishing the perception of balancethat is, a diversity of theoretical and methodological p erspectivesas well as actual balance. An appropriate mix of talent may facilitate a knowledg e base that furthers dissemination of research findings and improves the design of new re search studies. In this regard, the NRP would have benefited by formal inclusion of one or more methodologists. (Note 29) Alternatively, the research would have benefited fr om an officially appointed group of expert methodologists charged with translating the NRPs oversight into technically rigorous guidelines for design as well as data collection an d analysis. We could not find a description of how independent expert review of the final report was conducted. (Note 30) Moreover, a number of inconsistencies exist betwee n the official Summary (26 pages in length) of the report and the report itself (Shanahan, 2001). If Teaching Children to Read had been subjected to a more scrupulous review pri or to release, it would have had more potential to command a conse nsus. We acknowledge the severe time constraints under which the report was produced. Ho wever, the role of independent review is to verify and tighten the connections between ev idence and summary conclusions. This process is intended to screen out precisely the kin ds of inconsistencies and ambiguities that appear in the NRP documents.VII. ConclusionsThe impact of meta-analysis is strongly affected by two design decisions. First, the scientific due process for producing a study is critical to it s acceptance. How experts are assembled and provided with resources is as important as thei r charge. Secondly, the science itself is important. There is no single prescription for prod ucing meta-analyses, even though standards exist for general guidance. In spite of t he expertise of research teams, time, and
36 of 51resources available, variability among methodologic al approaches is probable. Meta-analyses designed to answer controversial ques tions must anticipate and address this concern. One strategy might be to assemble two diff erent teams of analysts at the onset of a study, each carrying out the five steps of meta-ana lysis. Another possibility may be to require methods for cross-validation in proposals i n response to a formal RFP (request for proposal). Of course, such elaborate procedures are not necessary for all meta-analyses. Rather, they are most relevant to those that affect critical policy decisions, such as the studies conducted by the NRP. In any case, experts (both substantive and methodological) who do not participate in a study should provide pe er review. (Note 31) Meta-analysis is an effective method of reading t he literature. Yet for many studies in the NRP database on phonics instruction, often little d etail was given regarding treatment implementation. The NRP analysts struggled with thi s issue as evidenced by the number of missing study descriptors in Appendix G. Without ca reful description of the treatments, their implementation, and the populations of students ser ved, it is doubtful that positive treatment effects can be understood well enough to disseminat e to teachers. And without such description, it may be impossible to understand why some treatments do not work as expected. Rigorous qualitative work in reading, whi ch the NRP is currently addressing (Manzo, 2003), has much potential to provide an eff ective link between theory development, program implementation, and quantitative research f indings. This reanalysis points to a number of moderator var iables that may play a prominent role in designing phonics instruction. Obviously, two treat ments nominally described as phonics and whole language cannot be directly compared if o ne uses classroom instruction while the other employs tutoring. We used regression analysis to sort out the effects of moderator variables. This provides an improvement to the onevariable breakdowns used in the NRP report. Based on the regression approach, we found that tutoring and language-based reading activities had effects at least as large as systema tic phonics. In addition, the data suggest these effects are additive. These results are stark ly different from the quantitative results presented in Teaching Children to Read but interestingly, they are very consistent with two conclusions: Programs that focus too much on the teaching of let ter-sounds relations and not enough on putting them to use are unlikely to be ve ry effective. In implementing systematic phonics instruction, educators must keep the end [original emphasis] in mind and insure that children understand the pur pose of learning letter-sounds and are able to apply their skills in their daily reading and writing activities. (NRP, 2000b, p. 2-96).Finally, it is important to emphasize that systemat ic phonics instruction should be integrated with other reading instruction to cre ate a balanced reading program. Phonics instruction is never a total readi ng program. (NRP, 2000b, p. 2-97). Despite the manifest consistency of these conclusio ns with the findings of the present report, the ideal role of meta-analysisto solve controvers ial issues and thus to improve educational practiceswas not directly fulfilled. T wo independent teams of researchers arrived at substantially different interpretations of the same evidence. If the NRP results are taken to mean that effective instruction in reading should focus on phonics to the exclusion of other curricular activi ties, instructional policies are likely to be
37 of 51misdirected. This interpretation of the data result s from a design in which simultaneous influences on reading interventions were not adequa tely coded and analyzed. In particular, early literacy policies are a timely concern, espec ially as they are interpreted and applied in the federal Early Reading First Program. Program ad ministrators and teachers need to understand that while scientifically-based reading research supports the role of phonics instruction, it also supports a strong language app roach that provides individualized instruction. As federal policies are formulated aro und early literacy curricula and instruction, it is important not to over-emphasize one aspect of a complex process. In our opinion, a sturdier methodology has potentia l to improve the estimates of the effect size in all substantive areas that the NRP examined. Analyses would also benefit from, indeed may require, a substantially larger sample o f studies. In this effort, researchers with substantive, methodological, and classroom experien ceas well as time and resourcesare necessary to find studies, and to propose and test alternative design strategies. While we applaud the NRP for taking the challenging and diff icult first steps in summarizing the extant knowledge on reading instruction, it is clea r that more work remains to be done.AcknowledgementThis research was completed with the generous suppo rt of The Pew Charitable Trusts. The opinions expressed in this report are those of the authors and do not necessarily reflect the views of The Pew Charitable Trusts. The authors wou ld also like to acknowledge the contributions of Mary Lee Smith and Joanne Yatvin.Notes 1. Results of this study were also reported in Ehri, N unes, Stahl and Willows (2001), and Ehri, Nunes, Willows, Shuster, Yaghoub-Zadeh, and S hanahan (2001). 2. Details of this selection process are given in Sect ion III. 3. Meta-analysis can also be performed with studies th at that do not examine treatment interventions (e.g., Hunter and Schmidt, 1990). We do not consider other genres of meta-analysis herein. 4. Meta-analysis is a labor-intensive research activit y. It is common to assemble research teams to facilitate the identification and coding o f studies within a reasonable amount of time. However, different coders should record the s ame study information with a limited margin of error. 5. Readers are referred to Hunt (1997) for an accessib le account of the story of meta-analysis. 6. The first estimate d = .41 is for outcomes at the conclusions of progra ms. The second estimate d = .44 is for end of program or end of school year, for programs lasting longer (Ehri et al., 2001, p. 414). 7. Fletcher and Lyon (1998) wrote In many studies, th e research was designed to evaluate the degree of explicitness required to teach word r ecognition skills. Instruction in word recognition skills, however, occurs along with oppo rtunities for applications to reading and writing, exposure to literature, and other practice s believed to facilitate the development of
38 of 51reading skills in proficient readers. This reflects one of the oldest observations of any form of teaching or traininga targeted skill cannot be learned without opportunities for practice and application. (pp. 59-60). 8. On p. 2-110 the outcome categories are given, but w e could find no rationale for this particular classification. 9. Yatvin (2002) reported that As time wound down, th e effects of insufficient time and support were all too apparent. In October 1999, wit h a January 31 deadline looming, investigations of many of the priority topics ident ified by the panel a year earlier had not even begun. One of those topics was phonics, clearl y the one of most interest to educational decision makers and to the public. Although the pan el felt that such a study should be done, the alphabetics subcommittee, which had not quite f inished its review of phonemic awareness, could not take it on at this late date. And so, contrary to the guidelines specified by NICHD at the outset, an outside researcher who h ad not shared in the panel's journey was commissioned to do the review (p. 368). 10. These did not include follow up comparisons. 11. Garan (2001) shared Yatvins concern that the NRP d id not use a consistent definition of reading. Garan also criticized the NRP meta-analysi s for being limited to a small number of studies and for conceptually dissimilar dependent v ariables. The latter two points, in our view, are problems common to both meta-analysis and narrative review. The degree to which they limit generalizability varies and cannot be determined a priori. 12. A re-examination that began at the problem formulat ion stage and proceeded to locating relevant studies would provide a more stringent cri terion for replicability. It would also be significantly more costly. Though we skipped these two steps, we would agree that problem formulation and data collection significantly shape d the NRPs study. 13. We excluded follow up comparisons, that is, any mea surements taken after post-test measurements were excluded from the analyses. 14. While some studies reported age, others reported gr ade. We converted all results to an approximate grade metric based on the formula grade = age 5. 15. This formula does not appear in Cooper and Hedges ( 1994). See Table 16.2 on p. 237. 16. In this simple case, one divides the class-level ef fect size by n. 17. We say distinct because each cohort involved diff erent groups of students. 18. The data analysis described on p. 1-10 appears to u se total n s as weights rather than the inverse variance weights described by Hedges and Ol kin (1985) on pp. 86 & 110. 19. In the future pure statistical weights might be u sefully applied when homogenous subsets of effect sizes are identified. 20. We used a highly conservative approach in the forwa rd stepwise selection of independent variables. We required a p -value of .01 (PIN) to enter and a p -value of .05 (POUT) for removal.
39 of 51 21. Organized language activities were observed in abou t 30% of both experimental and control comparisons. Note that effective language a ctivities in the experimental group will make the effect size larger while effective language activities in the contro l group will make the effect size smaller Thus, the two estimates logically have the opposi te sign. 22. The NRP deleted one study (Tunmer and Hoover, 1993) with d = 3.71 in obtaining the average effect size for tutoring. The value 3.71 ar ose as the average of 4 effect sizes for WordID (2.94), Spelling (1.63), Nonwords (1.49), an d Oral Reading (8.79). It is obvious that the last effect size is an extreme outlier, an d the NRP sensibly deleted this in its computations for tutoring. We surmise that this eff ect size was properly deleted from other computations. We also deleted this effect size (8.7 1) from our computations, but we included other effect sizes from this study, which ranged from .96 to 3.18. 23. It is interesting that the effect sizes for experim ental and control group language instruction are very nearly the same (taking into a ccount reversed signs), which supports the internal design consistency of the treatment coding s. 24. The gap is nearly zero at third grade, but widens s omewhat at higher grades. Students in later grades do benefit, but are more likely to rep resent populations of reading disabled students. 25. Material on the origins of meta-analysis was provid ed by Mary Lee Smith in a personal communication. 26. The Campbell Collaboration is an emerging internati onal effort that aims to help people make well-informed decisions by preparing, maintain ing, and promoting access to systematic reviews of studies on the effects of soc ial and educational policies and practices. More information is available at http://www.campbellcollaboration.org 27. This information is available at http://www.iom.edu/iom/iomhome.nsf/Pages/IOM+FAQs 28. Applicants who had taken strong stands supporting or opposing any particular approaches to reading instruction, or with a financ ial interest in commercial reading materials, were not considered, according to Duane Alexander, the director of the National Institute of Child Health and Human Development, wh o helped select the panel (Manzo, 2000). In addition, panelists could not be employee s of the Federal government. 29. Two expert consultants in methodology were introduc ed to the Panel in late January, 1999. It appears that both were made available to N RP members on an as needed basis. This information is available atwww.nationalreadingpanel.org/NRPAbout/Panel_Meeting s/01_21_99.htm. Note that the original deadline for the NRP report was January 31 1999. 30. There appears to be a collection of documents in wh ich the NRPs interactions are recorded. We do not know if this archive is availab le for public examination (see Yatvin, 2002). 31. The Campbell group, referenced above, provides desi gn review as a service. It does not appear to review drafts of final reports.
40 of 51 32. The K-3 NFT group size in the Gersten et al. (1988) study is reported as 45. Official documents give n = 21. 33. This model was sponsored by the Southwest Education al Development Laboratory. It stressed a developmental approach geared to childre n whose primary language was not English. In this approach primary language and cult ural background are essential to the learning process. 34. The next five effect sizes are from Camilli (1980). They are covariance adjusted based on a modified linear model that includes a linear s election rule. 35. This model was sponsored by the City University of New York. Rather than didactic methods, direct interaction with other children was the primary method of learning. Instructional games developed skills in the areas o f language, reading, and arithmetic. 36. This model was sponsored by the University of Flori da. The primary emphasis was on motivating parents, and teaching them to set and at tain their childrens educational goals. Parents spent time as instructional assistants as w ell as visiting other FT parents. 37. This model was sponsored by Northeastern Illinois U niversity. Entry language and experience of the children are built upon using a m ethod of language elicitation focusing on the use of oral language in all curriculum areas. 38. Dissertation study, see references. 39. For all reading and spelling outcomes, the amount o f growth (linear component) in each class was negatively related to initial PPVT-R stan dard deviations (using class as the unit of analysis).ReferencesCamilli, G. (1980). A Reanalysis of the Effect of F ollow Through on Cognitive and Affective Development (University of Colorado, Boul der). Dissertation Abstracts International, DAI-A 41/04, p. 1366, Oct 1980. Coles, G. (2003). Reading the Naked Truth Portsmouth, NH: Heinemann. Ehri, L., Nunes, S., Willows, D., Schuster, B., Yag houb-Zadeh, Z., and Shanahan, T. (2001). Phonemic awareness instruction helps children learn to read: Evidence from the National Reading Panel's meta-analysis. Reading Research Quarterly, 36, 250-287. Ehri. L., Nunes, S., Stahl, S., and Willows, D. (20 01). Systematic phonics instruction helps students learn to read: Evidence from the National Reading Panel's meta-analysis. Review of Educational Research, 71 (3), 393-447. Ehri, L. & Stahl, S. (2001). Beyond the Smoke and M irrors: Putting Out the Fire. Phi Delta Kappan 83(1), 17-20. Fletcher, J. M., & Lyon, G. R. (1998). Reading: A r esearch-based approach. In W. M. Evers (Ed.), What's gone wrong in America's classrooms (pp. 49-90). Stanford, CA: Hoover Institution Press.
41 of 51Foorman, B. R., Francis, D. J., Fletcher, J.M., Sch atschneider, C., & Mehta, P. (1998). The role of instruction in learning to read: Preventing reading failure in at-risk children. Journal of Educational Psychology 90, 1-19. Foorman, B., Francis, D., Novy, D. & Liberman, D. ( 1991). How letter-sound instruction mediates progress in first-grade reading and spelli ng. Journal of Educational Psychology 83(4), 456-469. Garan, E.M. (2001). Beyond the Smoke and Mirrors. Phi Delta Kappan 82(7), 500-506. Garan, E.M. (2002). Resisting reading mandates Portsmouth, NH: Heinemann. Glass, G. V, McGaw, B., & Smith. M.L. (1981). Meta-Analysis in Social Research Beverly Hills: SAGE Publications. House, E., Glass, G., McLean, L., & Walker, D. (197 8). No simple answer: Critique of the FT evaluation. Harvard Educational Review 48(2), 128-160. Hunt, M. M. How Science Takes Stock: The Story of Meta-Analysis (1997). NY: Russell Sage Foundation. Hunter, J.E. & Schmidt, F.L. (1990). Methods of Meta-Analysis Newbury Park, CA: SAGE Publications. Krashen, S. (2000, May 20). Reading Report: One Res earchs Errors and Omissions. Education Week 19(35), 48-50. Krashen, S. (2001). More smoke and mirrors: A criti que of the National Reading Panel (NRP) report on fluency. Phi Delta Kappan, 83(2), 118-22. Layzer, J., & Goodson, B. (2001). National Evaluation of Family Support Programs Cambridge, MA: Abt Associates, Inc. Lipsey, M.W. & Wilson, D.B. (1993). The efficacy of psychological, educational, and behavioral treatment: Confirmation from meta-analys is. American Psychologist 48(12), 1181-1209. Lovett, R., Ransby, M., Hardwick, N., Johns, M., & Donaldson, S. (1989). Can dyslexia be treated? Treatment-specific and generalized treatme nt effects in dyslexic childrens response to remediation. Brain and Language 37, 90-121. Manzo, K.K. (1998, February 18). New National Readi ng Panel faulted before its formed. Education Week 27(23), 18. Manzo, K.K. (2000, April 19). Reading Panel Urges P honics For All in K-6. Education Week 19(32), 1 & 14. Manzo, K.K. (2002, January 30). New Panels to Form to Study Reading Research. Education Week 21(20), 5. Manzo, K.K. & Hoff, D.J. (February 5, 2003). Federa l Influence Over Curriculum Exhibits Growth. Education Week 22(21), 1 & 10 & 11.
42 of 51McCartney, K. & Rosenthal, R. (2000). Effect size, practical importance, and social policy for children. Child Development 71, 173-180. McCartney, K. & Dearing, E. (2002). Evaluating Effe ct Sizes in the Policy Arena. The Evaluation Exchange Newsletter 8(1), 4 & 7. National Reading Panel. (2000a). Teaching Children to Read: An Evidence-Based Assessment of the Scientific Research Literature on Reading and its Implications for Reading Instruction Washington, D.C.: NICHD. National Reading Panel (2000b). Alphabetics Part II : Phonics Instruction (Chapter 2) in Report of the National Reading Panel: Teaching Children to Read: An Evidence-Based Assessment of the Scientific Research Literature on Reading and its Implications for Reading Instruction: Reports of the Subgroups Rockville, MD: NICHD Clearinghouse. Orwin, R. G. (1994). Evaluating coding decisions. P p. 140-162 in H. Cooper & L.V. Hedges (Eds.). The handbook of research synthesis. New York, NY: Russel Sage. Pressley, M. & Allington, R. (1999). Concluding ref lections: What should reading research be the research of. Issues in Education 5(1), 165-175. Shadish, W.R. & C.K. Haddock (1994). Combining esti mates of effect size, pp. 261-281. In Cooper, H. & L.V. Hedges (eds.), The Handbook of Research Synthesis New York: Russell Sage Foundation. Shanahan, T. (2001). Response to Elaine Garan: Teac hing Should be Informed by Research, Not Authoritative Opinion. Language Arts Journal 79(1), 71-72. Tunmer, W. E., & Hoover, W. A. (1993). Phonological recording skill and beginning reading. Reading and Writing: An Interdisciplinary Journal 5. 161-179. Vickery, K.S., Reynolds, V.A., & Cochran, S.W. (198 7). Multisensory teaching approach for reading, spelling, and handwriting, Orton-Gilli ngham based curriculum, in a public school setting. Annals of Dyslexia, 37, 189-200. Yatvin, J. (2000). Minority View. In National Research Panel, Teaching Children to Read: An Evidence-Based Assessment of the Scientific Rese arch Literature on Reading and its Implications for Reading Instruction pp. 1-6. Washington, D.C.: NICHD. Yatvin, J. (2002). Babes in the Woods: The Wanderin gs of the National Reading Panel. Phi Delta Kappan 83 (5), 364-369.About the AuthorsGregory Camilli Rutgers University 10 Seminary PlaceNew Brunswick, NJ 08901 732.932.7496 X8350 firstname.lastname@example.org
43 of 51 Gregory Camilli is Professor in the Rutgers Graduat e School of Education. His interests include measurement, program evaluation, and policy issues regarding student assessment. Dr. Camilli teaches courses in statistics and psych ometrics, structural equation modeling, and meta-analysis. His current research interests i nclude school factors in mathematics achievement, technical and validity issues in highstakes assessment, and the use of evidence in determining instructional policies.Sadako Vargas As Assistant Professor at Kean University, and Adju nct Professor at Touro College and Seton Hall University, Sadako Vargas has taught in the areas of research methods and occupational therapy. Her interests lie in the use of meta-analysis for investigating intervention effects in the area of rehabilitation specifically related to pediatrics and occupational therapy intervention.Michele Yurecko Michele Yurecko is a Ph.D. student in Educational P sychology with a concentration in educational measurement at the Graduate School of E ducation, Rutgers University. Her academic interests include the study of research me thods and design applied to the field of education, and the intersection of educational rese arch, testing and public policy. Appendix AAdditional StudiesStudy ID 63Barr, R. (1974). The effect of instruction on pup il reading strategies. Reading Research Quarterly 10, 555-582. This study compared a phonics with a sight word met hod of instruction. Word learning tasks, word recognition, and comprehension were tested. The process by which subject were assigned to groups was not descr ibed, but it was reported that the groups did not differ in age or readiness as me asured by the World Learning Tasks. Outcome variables for effect size computatio n were reported in terms of substitution errors on word reading tasks. 65Peterson, M.E. & Haines, L.P. (1992). Orthographi c analogy training with kindergarten children: Effects on analogy use, phon emic segmentation, and letter-sound knowledge. Journal of Reading Behavior 24, 109-127. This study examined the effect of teaching orthogra phic analogies based on words that rhyme. Children were tested on segmentation ab ility, letter-sound knowledge, and reading words by analogy. Subjects were stratif ied on ability measures, and then assigned by odd and even numbers (sequential r anks) to treatment and control groups.
44 of 51 68Gillon, G. & Dodd, B. (1997). Enhancing the phono logical processing skills of children with specific reading disability. European Journal of Disorders of Communication 32, 67-90. This study compared a 20-hour phonological training program to two groups tested in a previous study published in 1995. We us ed the original 1995 data in which a group receiving 12-hour phonological traini ng was compared with a group receiving 12-hour semantic syntactic training Groups were tested with the Neale Analysis of Reading Ability Revised .Appendix BCase Studies of Three Selected StudiesGersten, Darch, & Gleason (1988)This study used select data from the Follow Through (FT) Planned Variation Experiment, which aimed to increase the achievement and self-co ncepts of children from economically disadvantaged backgrounds. To give some background, the Follow Through program was intended to pick up where Head Start ended, and mai ntain presumed academic gains from Kindergarten to third grade. According to White et al. (1973, Volume II) [Follow Through] is intended to be a comprehensive project offering educational, medical and dental, nutritional, socia l, and psychological services to children previously enrolled in Head Start. Foll ow Through uses a strategy of planned variation in approaches to early elementa ry education, and 20 different models are being implemented in Follow Th rough sites across the nation. (p. 83). Fourteen education models (i.e., different treatmen ts) were included in the FT Evaluation (Stebbins et al., 1973), and these varied in the de gree of classroom structure, basic skills, and parental involvement. One such model was Direct Instruction (DI), sponsored by the University of Oregon, College of Education. In the DI approach, behavioral methods were used with highly structured teaching materials. Tea chers worked with small groups of students, and tests were frequently administered to assess childrens progress. There were two cohorts of students from East Saint Louis, Illinois. Each consisted of a treatment (FT) group receiving DI and Non-Follow Th rough comparison (NFT) group. One cohort was assessed from grades 1-3 ( n = 96, 45 for FT, NFT), the other from K-3 ( n = 56, 21 for FT, NFT). (Note 32) These were the groups providing data for the Gerst en et al. (1988) study. Nationally, however, Direct Instructi on was implemented at 9 other sites. Outcome measures included the Metropolitan Achievem ent Test with subtest scores in Word Knowledge, Spelling, Language, and Reading, am ong others. The NRP analysts choose to compute effect sizes for Reading ( d = .11, 28) and Spelling ( d = .12, .16) for the two cohorts. The Reading effect size was classified as a measure of comprehension. The effect sizes were quite close to calculations from the present study of (.09, 27) for Reading and (.10, .15) for Spelling. Similar national-level esti mates of .14 and .12 for Reading and Spelling (for the K3 cohort only), respectively, were given by Camilli (1980). Overall, the results from East Saint Louis are rema rkably representative of the national results, but since Direct Instruction was only 1 of 14 other models, we might ask which
45 of 51models showed the largest gains in Reading and Spel ling. Camilli (1980) found that two models with the largest Reading effect sizes were L anguage Development ( d = .180) ( Note 33 ; Note 34 ) and Interdependent Learning ( d = .168) ( Note 35 ). In Spelling, the Parent Education (Note 36) ( d = .310) and Cultural Linguistic (.341) (Note 37) models had the largest gains. We would add that the Direct Instruc tion model had the largest gain for MAT Language, Part B ( d = .327), in which a student was required to recogn ize asking, telling, and incomplete sentences.In conclusion, our statistical results are close, i n this case, to those of the NRP analysts. Thus, our extended analysis of the Gersten et al. ( 1988) study can be taken as validation of the consistency of their methodology. However, this case study points to other aspects of the NRP study in terms of its generalizability, or exte rnal validity. It is ironic that a single study can strengthen conclusions regarding the value of p honics instruction, and yet the study was originally embedded in a larger study that provided mixed findings with regard to treatment efficacy. Though it is true that the basic skills m odels (Direct Instruction and Behavior Analysis) had the largest overall gains in the Foll ow Through experiment, the Direct Instruction model did not outperform other models f or Reading or Spelling. Data from FT models other than Direct Instruction w ere not included in the phonics instruction meta-analysis for several probable reas ons. First, it is doubtful that reports such as those by House et al. (1978) would be identified with the NRP key word searches. It would be virtually impossible in a meta-analysis to anticipate such studies without direct knowledge of their existence. Studies like Camilli (1980) (Note 38) or the FT evaluation reports (e.g., Stebbins et al.., 1977) would not be included because they do not appear in refereed journals. However, even if such studies we re located and included, a dilemma would arise because both the NFT and other FT model s could serve as controls. Only if enough information were reported for comparing the level of phonics instruction in the alternative treatments could a consistent decision be made. This might be possible even though the data are about 30 years old, but such an in-depth analysis would not be economically feasible.Tunmer, W. E., & Hoover, W. A. (1993)This study compared the effects of three different language programs on beginning readers who had been identified as having reading difficult ies. Two types of Reading Recovery programs were used for the treatment groups, and th e standard intervention program was used for the control.The first treatment group was the Standard Reading Recovery (SRR) program, which is a remedial reading program developed in New Zealand t o reduce the number of children with reading and writing difficulties. At risk children were selected and provided with 30-40 minutes per day of individual instruction by a trai ned teacher for a period of 12-20 weeks. Reading Recovery lessons followed the procedures de veloped by Clay (1985) and usually included seven activities, one of which was writing a story the child had created. Writing exercises employed phonological awareness training techniques to isolate individual sounds in familiar printed words. Incidental word analysis activities that arose from the childrens responses were available after the children mastere d letter identification. This instruction was given in addition to the childrens regular cla ssroom activities. The second treatment group was the Modified Reading Recovery (MRR) program. It held the parameters of the standard program constant and then added explicit and systematic
46 of 51instruction in phonological recoding skills to the letter identification activities of the standard Reading Recovery program. The control grou p was the Standard Intervention Group. It received support services that were norma lly available to at risk readers, mostly funded by the (then) Chapter 1 program. Children we re instructed in small groups, and instructional techniques varied greatly and include d word analysis activities. First graders with mean age of 6 years 2 months at the beginning of the school year were drawn from a pool of at risk readers from 30 school s across 13 school districts. The lowest ranked children from each school were given the Dia gnostic Survey and Dolch Word Recognition tests. Three matched groups were formed from those who performed at the lowest levels on these tests. The 64 children in th e two Reading Recovery treatment groups were drawn from 34 classrooms from 23 schools. The control group of 32 students was drawn from 13 classrooms in 7 schools. Classrooms w ere roughly matched on location, SES and type of classroom reading program. No signi ficant differences were observed between the means of the three comparison groups fo r age and all pre-treatment measures. The study also reports that two additional control groups of 32 children each were added (p. 170), but there is no further mention of these latt er groups. For this study, the NRP analysts choose two groups, the MRR group and the Standard Intervention group. Effect sizes were then computed for 4 outcome categories: Word ID ( d = 2.94), Spelling ( d = 1.63), Nonwords ( d = 1.49), and Oral Reading ( d = 8.79). These effect sizes, especially the latter, seem very large, and this could be taken to mean that the effects of systematic phonics instruction were quite impres sive. However, it should be noted that systematic phonics instruction was the key element in the MRR group that distinguished it from SRR. By comparing these two groups, we can obt ain an estimate of how much improvement resulted from this modification to the standard program. We calculated these effect sizes as Word ID ( d = -.12), Spelling ( d = -.25), Nonwords ( d = -.12), and Oral Reading ( d = .12). These results indicate that these two grou ps performed at very similar levels.The large SRR effect sizes may be due to either the size of the treatment unit or the RR treatment itself, but these two factors are complet ely confounded in this study. While the children in both Modified and Standard Reading Reco very groups received one-to-one tutoring, the children in the Standard Intervention group received small group treatment. In fact, the authors warned that It is important to note, however, that the highly s ignificant results in favor of the two Reading Recovery groups over the standard inter vention may not have been due to the Reading Recovery program per se (i.e., t he diagnostic procedures, the format of the Reading Recovery lessons, the procedu res for discontinuation) but rather to the manner in which the instruction was d elivered. Reading Recovery involved one-to-one instruction, whereas the standa rd intervention involved instruction in small groups. (pp. 172-173) It is arguable, in fact, that taking the authors w isdom into account would result in an effect size for Oral Reading of d = .12 in contrast the NRP estimate of d = 8.79. Once again, we see that there is a significant issue involved in d etermining the definition of control group. Whereas the NRP guidelines clearly designate the st andard intervention as having the least systematic phonics instruction, it is the compariso n of the MRR and SRR groups that is most germane to estimating the systematic phonics e ffect (in our study represented as the TP2 contrast).
47 of 51Foorman, B., Francis, D., Novy, D. & Liberman, D. ( 1991) This study explored the relationship among phonemic segmentation, word reading and spelling, with the intention of demonstrating the s uperiority of a more letter-sound (labeled More-LS) approach of reading instruction. Childre n receiving less letter-sound instruction (labeled Less-LS) were not expected to exhibit re gularity effects in word reading to the same extent or at the same rate as children receivi ng More-LS instruction. Two groups were selected to participate in this stu dy. The Less-LS group was comprised of 40 students enrolled in three first grade classroom s in a Houston, Texas, public school. The More-LS group was comprised of 40 students in three first grade classrooms in two Houston parochial schools. Students in all six classes rece ived one hour of reading instruction daily, and both groups used a basal reading series. Childr en enrolled in the parochial schools were younger by about 2 months on average (p < .05); and they had higher initial reading and PPVT (Peabody Picture Vocabulary) scores, though th e latter differences were not significant. Public school classes had, on average, a PPVT standard deviation about 60% larger than that of parochial school classes.Neither the treatment nor the control regimen was d esigned or manipulated by the researchers; both reflected the regular teaching ha bits of the individual classroom teachers. Teachers in the three public school classrooms were described as being committed to dealing with whole words in meaningful contexts, and described themselves as using a language experience strategy to teach reading. Th e Less-LS teachers used daily story selections from the basal series Harcourt Brace Jovanovitch Reading to provide a theme around which instruction was based. Teachers in the three parochial school classrooms were described as being committed to letter-sound corre spondences and having children segment and blend sounds in isolation. (p. 458). Rules for relating letters and sounds, and sequenced spelling patterns were taught using Scott, Forseman Reading, Phonics Practice Readers, Series B and Modern Curriculum Press Phonic Program (a workbook). Approximately 45 of the 60 minutes devoted to reading instruction we re spent on letter-sound activities. A Scott Forseman basal reading series was also used. The study was approximately ten months in duration. Students were administered pre-test measures in October of first grade, with post-test measures administered the following February and May. The following tests were administ ered: Gates-MacGinitie Reading Test, Basic R, Form 1; Peabody Picture Vocabulary Test Revised, Form L; a spelling test (researcher-made test consisting of 40 regular and 20 exception words), a word reading test (researcher-made test consisting of 40 regular and 20 exception words); and the 13 item Test of Auditory Analysis Skills, TAAS. There were no si gnificant posttest group differences in TAAS mean scores or trends. There were significant differences in trends of spelling scores (both regular and exception words) and trends of wo rd reading scores (both regular and exception words) favoring the more LS-group. In oth er words, the more LS-group appeared to improve at a faster rate than the Less-LS group in word reading and spelling. For the three primary outcome variables (Word Readi ng, Spelling and TAAS), the researchers did not report standard deviations. In this instance, it appears that the NRP analysts used the simple standard deviation (for th e effect size denominator) of class means. According to standard statistical theory, this resu lts in an effect size that is too large by a factor of n where n is the number of students in the classes. The NRP effect sizes for Word ID ( d = 1.92), Decoding ( d = 1.67), and Spelling ( d = 2.21) are not comparable to those of
48 of 51other studies in which the individual student is th e basis for standard deviation calculations. In this case, we converted the effect size to the i ndividual student metric and obtain the following: Word ID ( d = .48), Decoding (.62), and Spelling (.49). On ave rage, the effect sizes are 3-4 times smaller than those computed by the NRP analysts, which reflect class sizes of about 13 (for participating subjects). Mor eover, approximate matching does not completely resolve the issue of what portion of the adjusted d s should be attributed to treatment, school type (public versus parochial), a nd school-by-treatment interaction. In conclusion, the Foorman study for the most part succeeded at controlling initial differences. However, there is some evidence to sug gest that the public school students lagged slightly behind their parochial school count erparts, and that individual differences in ability (PPVT-R) were somewhat larger in the public school classrooms. ( Note 39 ) We do not know the degree to which this initial dif ference may have affected posttest differences or rates of growth. However, it is clea r that the effect sizes need to be adjusted to the individual student metric.Appendix CDescription ofVickery, K.S., Reynolds, V.A., & Cochran, S.W. (198 7). Multisensory teaching approach for reading, spelling, and handwr iting, Orton-Gillingham based curriculum, in a public scho ol setting. Annals of Dyslexia, 37, 189-200.The study reports the results of a four-year study (1978 1981) that investigated the effect of the Multisensory Teaching Approach for Reading, Spelling and Handwriting (MTARSH) in both remedial and nonremedial classes in a publi c school. The study reports the result of California Achievement Test, which were administere d annually in April of each year. The MTARSH was developed by adapting the individualized OrtonGillingham-Stillman method to small homogenous groups of students. The MTARSH employs two basic decoding techniques, synthesizing phonics and memor izing whole words. The authors report the baseline scores for each gra de and the posttest scores of both remedial and nonremedial classes (separately) taken after 1, 2, 3 and 4 years MTARSH instruction. The remedial classes were composed of students who qualified for Chapter 1 or special Education/LLD program, at risk of presenting readin g difficulties. All other children enrolled in this school were classified as non-reme dial. The MTARSH Program was employed for all students, both remedial and non-re medial, in this school ( n = 426 during the four years covered by this study). The amount o f instruction received is equal for both groups25-minutes per day for the first graders an d 55 minutes of daily instruction for grades 2 through 6. For the remedial classes, MTARS H program was their only instruction in reading, spelling, and cursive writing. The nonremedial classes MTARSH program was taught in lieu of the regular state-adopted spellin g and handwriting programs, using the supplemental reading materials and the basal reader s. Although detailed instructional method and materials were different in two groups, the MTARSH method used in both classes was treated as comparable in this study.The baseline score is from the pre-tests administer ed two years prior to the introduction of the MTARSH program. The intervention effect was mea sured by the difference between the
49 of 51 baseline scores and the posttest scores. The analys is was conducted separately for remedial group and nonremedial groups. The NRP reports eight effect sizes for this study under general reading category. (Alphabetics, Part II. Ap pendix G. page: 2-174). Effect sizes are reported for 3rd 4th, 5th and 6th grades for both r emedial and non-remedial groups, which yielded the 8 effect sizes computed by the NRP team Through recalculation of the effect sizes using the formula reported (NRP Report, page 1-10) and the sample sizes reported in Appendix G, it was verified that the NRP used basel ine averages as the control group outcome, and the one-year follow-up test averages a s the experimental outcome. The effect sizes were reported to represent the magnitu de of performance differences between the phonic instruction (OrtonGillingham method) an d regular class instruction that was provided before the MTARSH was instituted. This stu dy examined the effect of one instructional method on two different populations; no control group, or other instructional method, was available for comparison. The design is clearly pre-post and does not satisfy a strict interpretation of the quasi-experimental req uirement for inclusion (NRP, pp. 1-7 to 1-9). The World Wide Web address for the Education Policy Analysis Archives is epaa.asu.edu Editor: Gene V Glass, Arizona State UniversityProduction Assistant: Chris Murrell, Arizona State University General questions about appropriateness of topics o r particular articles may be addressed to the Editor, Gene V Glass, email@example.com or reach him at College of Education, Arizona State University, Tempe, AZ 8 5287-2411. The Commentary Editor is Casey D. Cobb: firstname.lastname@example.org .EPAA Editorial Board Michael W. Apple University of Wisconsin David C. Berliner Arizona State University Greg Camilli Rutgers University Linda Darling-Hammond Stanford University Sherman Dorn University of South Florida Mark E. Fetler California Commission on Teacher Credentialing Gustavo E. Fischman California State UniveristyLos Angeles Richard Garlikov Birmingham, Alabama Thomas F. Green Syracuse University Aimee Howley Ohio University Craig B. Howley Appalachia Educational Laboratory William Hunter University of Ontario Institute ofTechnology Patricia Fey Jarvis Seattle, Washington Daniel Kalls Ume University Benjamin Levin University of Manitoba Thomas Mauhs-Pugh Green Mountain College
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