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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 +8 percentile points in one study across two comparisons, with a range of –10 to +29 percentile points across findings. The average improvement index for comprehension is +3 percentile points in one study across two comparisons, with a range of –2 to +15 percentile points across findings.
Summary
The WWC reviewed one study on Read, Write & Type!™, which met WWC evidence standards. Based on the study's results, the WWC found the program to have potentially positive effects in the alphabetics domain and no discernible effects in the comprehension domain. The evidence presented in this report may change as new research emerges.
|Institute of Education Sciences