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Research
Two studies reviewed by the WWC investigated the effects of Literacy Express in center-based settings. Both studies (Lonigan, 2006; Lonigan, Farver, Clancy-Menchetti, & Phillips, 2005) were randomized controlled trials that met WWC evidence standards. Lonigan (2006) included 17 public preschool centers in northern Florida. Almost two-thirds of the children were African-American. The study author compared oral language, print knowledge, phonological processing, and math outcomes using data from year two of the study for children participating in a Literacy Express intervention group, a DLM Express plus Open Court Pre-K intervention group, or a business-as-usual comparison group.5
Lonigan et al. (2005) included 48 preschools from Tallahassee, Florida, and Los Angeles, California. A majority of the preschools were Head Start centers and more than three-quarters of the children were African-American or Hispanic. The study authors compared oral language, print knowledge, phonological processing, and cognition outcomes for children who participated in a Literacy Express with professional development via workshops group (the "workshop group") or a Literacy Express with professional development via workshops plus mentoring group (the "mentoring group"), or a business-as-usual comparison group.6
Extent of evidence
The WWC categorizes the extent of evidence in each domain as small or medium to large (see the What Works Clearinghouse Extent of Evidence Categorization Scheme). The extent of evidence takes into account the number of studies and the total sample size across the studies that met WWC evidence standards with or without reservations.7
The WWC considers the extent of evidence for Literacy Express to be medium to large for oral language, print knowledge, and phonological processing, and small for cognition and math. No studies that met WWC evidence standards with or without reservations addressed early reading/writing.
6 The study authors combined the two intervention groups, and the WWC used the combined data to determine the rating of effectiveness for this WWC intervention report. The study authors' analyses for the comparisons between the individual intervention groups and the business-as-usual comparison group are included in Appendices A4.1–A4.4 and the comparison between the mentoring and workshop groups is included in the report and in Appendices A5.1–A5.4.
7 The Extent of Evidence Categorization was developed to tell readers how much evidence was used to determine the intervention rating, focusing on the number and size of studies. Additional factors associated with a related concept, external validity, such as the students' demographics and the types of settings in which studies took place, are not taken into account for the categorization.
