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Effectiveness
Findings
The WWC review of interventions for English language learners addresses student outcomes in three domains: reading achievement, English language development, and mathematics achievement. The studies included in this report cover only two domains: reading achievement and English language development. The findings that follow present WWC-calculated estimates of the size and the statistical significance of the effects of Read Well® on English language learners.9
Reading achievement. Frasco (2008) reported a not statistically significant difference in reading gains, as measured by the Dynamic Indicators of Basic Literacy Skills (DIBELS) Nonsense Word Fluency subtest, and a not statistically significant difference in fluency and comprehension gains, as measured by the Gray’s Oral Reading Test–Fourth Edition (GORT-4).10 The average effect size across these outcomes was not large enough to be considered substantively important according to WWC criteria.
English language development. Frasco (2008) reported a positive and statistically significant difference in vocabulary gains as measured by the Peabody Picture Vocabulary Test–Third Edition (PPVT-III). However, WWC calculates significance based on posttest standard deviations (as opposed to the study, which used standard deviations of pretest to posttest gains); after this adjustment, the WWC found that the difference in vocabulary gains was not statistically significant. The effect size is large enough to be considered substantively important according to WWC criteria.
Rating of effectiveness
The WWC rates the effects of an intervention in a given outcome domain as positive, potentially positive, mixed, no discernible effects, potentially negative, or negative. The rating of effectiveness takes into account four factors: the quality of the research design, the statistical significance of the findings, the size of the difference between participants in the intervention and the comparison conditions, and the consistency in findings across studies (see the WWC Procedures and Standards Handbook, Appendix E).
9 The level of statistical significance was reported by the study authors or, when necessary, calculated by the WWC to correct for clustering within classrooms or schools and for multiple comparisons. For an explanation, see the WWC Tutorial on Mismatch. For the formulas the WWC used to calculate the statistical significance, see WWC Procedures and Standards Handbook, Appendix C for clustering and WWC Procedures and Standards Handbook, Appendix D for multiple comparisons. For the Read Well® studies summarized here, no corrections for clustering or multiple comparisons were needed. However, the WWC calculates statistical significance based on posttest standard deviations and not on pretest to posttest gains; this adjustment was applied to the Frasco (2008) study.
10 The study also includes results on the Comprehensive Test of Phonological Processing. The English Language Learners area does not consider phonological awareness measures as part of the reading achievement or English language development domains. Therefore, these results are not included in this review.