Found effects

The WWC found Waterford Early Reading Level One™ to have no discernible effects on oral language or on print knowledge

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 oral language is 0 percentile points for the study, with a range of –3 to +3 percentile points across findings. The average improvement index for print knowledge is +7 percentile points for the study, with a range of –4 to +13 percentile points across findings.

Findings for comparisons between Waterford Early Reading Level One™ and Let’s Begin with the Letter People®

The data for the comparison described below were included in the Fischel et al. (in press) study, but they do not contribute to the overall rating of effectiveness because the WWC included the comparison of Waterford Early Reading Level One™ with the business-as-usual comparison group in the rating for the same study, which provides the most direct evidence of Waterford’s effects. However, the WWC believes that the findings from this comparison provide useful information to practitioners who may be interested in comparing the effects of different curricula. The WWC reports the findings for comparisons of Waterford Early Reading Level One™ and Let’s Begin with the Letter People® here and in Appendices A4.1 and A4.2.

Oral language. Fischel et al. (in press) included data for two measures in this outcome domain. The differences between the Waterford Early Reading Level One™ and Let’s Begin with the Letter People® groups were not statistically significant for either measure as calculated by the WWC, and the average effect size was neither statistically significant nor large enough to be considered substantively important according to the WWC criteria (that is, at least 0.25). The average improvement index for oral language is –1 percentile point (Waterford Early Reading Level One™ is the intervention group and Let’s Begin with the Letter People® is the comparison group), with a range of –2 to +1 percentile points across findings.

Print knowledge. Fischel et al. (in press) included data for six measures in this outcome domain. The difference between the Waterford Early Reading Level One™ and Let’s Begin with the Letter People® groups was not statistically significant for any of these measures as calculated by the WWC, and the average effect size was neither statistically significant nor large enough to be considered substantively important according to the WWC criteria (that is, at least 0.25). The average improvement index for print knowledge is –3 percentile points (Waterford Early Reading Level One™ is the intervention group and Let’s Begin with the Letter People® is the comparison group), with a range of –13 to +2 percentile points across findings.

Summary

The WWC reviewed three studies on Waterford Early Reading Level One™. One of these studies met WWC evidence standards; the remaining studies did not meet WWC evidence screens. Based on this study, the WWC found no discernible effects on oral language and print knowledge. Additional findings that were not considered for the rating of effectiveness indicated that Waterford Early Reading Level One™ and Let’s Begin with the Letter People® affect children’s outcomes similarly in the oral language and print knowledge domains. The evidence presented in this report may change as new research emerges.

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