Found effects

The WWC found Corrective Reading to have potentially positive effects on alphabetics and fluency and no discernible effects on comprehension

Improvement index

The WWC computes an improvement index for each individual finding. In addition, within each outcome domain, the WWC computes an average improvement index for each study and an average improvement index across studies (see Technical Details of WWC-Conducted Computations). The improvement index represents the difference between the percentile rank of the average student in the intervention condition versus the percentile rank of the average student in the comparison condition. Unlike the rating of effectiveness, the improvement index is based entirely on the size of the effect, regardless of the statistical significance of the effect, the study design, or the analyses. The improvement index can take on values between -50 and +50, with positive numbers denoting results favorable to the intervention group.

The average improvement index for alphabetics is +9 percentile points across all findings in the single study, with a range of +1 to +13 percentile points. The improvement index for the single outcome for fluency is +11 percentile points. The average improvement index for comprehension is +7 percentile points across all findings in the single study, with a range of +2 to +11 percentile points.

Summary

The WWC reviewed 25 studies on Corrective Reading. One study met the WWC evidence standards. ¹ Based on this one study, the WWC found potentially positive effects in the alphabetics and fluency domains and no discernible effects in the comprehension domain. The evidence presented in this report may change as new research emerges.