Scholarly reviews are unanimous in concluding that Direct Instruction (DI) programs are highly effective. In contrast, the WWC has found very few studies of DI that meet its criteria for review and has concluded that there is little evidence to support the programs’ efficacy. This report analyzes why these conclusions differ so markedly from the scholarly literature. The first section discusses issues related to the WWC’s criteria regarding exclusion or inclusion of studies and their review procedures. Areas discussed include the ways in which reviews focus on narrow curricular programs, fail to examine or consider the characteristics of the programs, apply an arbitrary time limit to the included studies, and use standards for review that differ markedly from those generally used in the social sciences, excluding most field-based studies and those using advanced statistical methods. The second section examines studies of DI programs that the WWC has found to meet their inclusion criteria and documents serious errors in a large proportion of these decisions. The third and fourth sections analyze content of the WWC report on Reading Mastery and students with learning disabilities that was initially posted in July 2012, reviewing errors in inclusion and exclusion of studies. Over twenty research studies that could have been included in the WWC review are examined, detailing the design and conclusions of the studies, the effect size associated with their results, and reasons that the WWC might reject the study for inclusion. The effect sizes are statistically analyzed. There was no indication that the criteria used by the WWC to select or exclude studies from consideration were related to the reported results. The report concludes that the WWC procedures appear to result in a selective and inaccurate view of the DI literature. It suggests that consumers would be well advised to consult sources of summary material other than the WWC and, especially, the well-conducted and highly regarded meta-analysis literature.
In Memory of
Siegfried "Zig" Engelmann
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Tuesday, April 07, 2026
