Found effects

The WWC found Waterford Early Reading Program™ to have potentially positive effects on alphabetics 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 +19 percentile points for the single study, with a range of –26 to +37 percentile points across findings. The improvement index for the single outcome in the comprehension domain is +4 percentile points.

Summary

The WWC reviewed 36 studies on Waterford Early Reading Program™. One study met WWC evidence standards with reservations; the remaining studies did not meet WWC evidence screens. Based on the one study, the WWC found potentially positive effects on alphabetics and no discernible effects on comprehension. The evidence presented in this report may change as new research emerges.