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Effectiveness
Findings
The WWC review of interventions for early childhood education addresses children's outcomes in six domains: oral language, print knowledge, phonological processing, early reading/writing, cognition, and math. Lonigan (2006) and Lonigan et al. (2005) addressed outcomes in the oral language, print knowledge, phonological processing, cognition, and math outcome domains. The findings below present the authors' and the WWC-calculated estimates of the size and statistical significance of the effects of Literacy Express on children's performance. 8
Oral language. Lonigan (2006) analyzed group differences between the Literacy Express and business-as-usual comparison groups for two measures of oral language—the Peabody Picture Vocabulary Test-III (PPVT-III) and the Preschool Comprehensive Test of Phonological and Print Processes (P-CTOPPP) Definitional Vocabulary subtest. The differences between the groups were not statistically significant for either outcome; however, the average effect size across measures was large enough to be considered substantively important according to WWC criteria (that is, at least 0.25).
Lonigan et al. (2005) analyzed group differences between the combined Literacy Express group and the business-as-usual comparison group for one measure of oral language—the Preschool Language Scales-IV (PLS-IV) Expressive Communication subscale. The difference between groups was statistically significant and favored children in the Literacy Express group.
Print knowledge. Lonigan (2006) found a statistically significant difference favoring children in the Literacy Express group on three of the five outcome measures assessed in this domain—the Test of Early Reading Ability-3 (TERA-3) Alphabet and Meaning subtests and the Woodcock-Johnson III (W-J III) spelling subtest. These effects were confirmed to be statistically significant by the WWC. The author found no statistically significant differences between the intervention and business-as-usual comparison groups on the other two measures (TERA-3 Print Conventions subtest and P-CTOPPP Print Knowledge subtest). The average effect size across measures was large enough to be considered substantively important according to WWC criteria (that is, at least 0.25).
Lonigan et al. (2005) found a statistically significant difference favoring children in the combined Literacy Express group on the one outcome measure assessed in this domain (P-CTOPPP Print Knowledge subtest).
Phonological processing. Lonigan (2006) analyzed group differences between the Literacy Express and business-as-usual comparison groups for two measures of phonological processing (P-CTOPPP Blending subtest and P-CTOPPP Elision subtest) and found statistically significant differences favoring the intervention group for both measures. The statistical significance of these effects was confirmed by the WWC.
Lonigan et al. (2005) analyzed group differences between the combined Literacy Express group and business-as-usual comparison groups for the same two measures of phonological processing and found statistically significant differences favoring the intervention group for the Elision subtest. The WWC confirmed the statistical significance of this effect. The authors found no statistically significant difference between groups on the Blending subtest; however, the average effect size across these two measures was large enough to be considered substantively important according to WWC criteria (that is, at least 0.25).
Cognition. Lonigan et al. (2005) found no statistically significant differences between the combined Literacy Express group and the business-as-usual comparison group for any of the three measures assessed in this domain (P-CTOPPP Non-Word Repetition subtest; P-CTOPPP Word Span subtest; P-CTOPPP Rapid Object Naming subtest). Additionally, the average effect size across measures was not large enough to be considered substantively important according to WWC criteria (that is, at least 0.25).
Math. Lonigan (2006) found a statistically significant difference favoring children in the Literacy Express group on one of the two outcome measures assessed in this domain—Children's Math Assessment (CMA), Abbreviated Version—and this effect was confirmed to be statistically significant by the WWC. The author found no statistically significant difference between the intervention and business-as-usual comparison groups on the W-J III Applied Problems subtest. However, the average effect size across these two measures was large enough to be considered substantively important according to WWC criteria (that is, at least 0.25).
Rating of effectiveness
The WWC rates the effects of an intervention in a given outcome domain as positive, potentially positive, mixed, no discernible effects, potentially negative, or negative. The rating of effectiveness takes into account four factors: the quality of the research design, the statistical significance of the findings,8 the size of the difference between participants in the intervention and the comparison conditions, and the consistency in findings across studies (see the WWC Intervention Rating Scheme).
