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Research
Twelve studies reviewed by the WWC investigated the effects of CWPT. One study (Greenwood, Terry, Utley, Montagna, & Walker, 1993) was a randomized controlled trial that met WWC evidence standards. The remaining 11 studies did not meet WWC evidence screens.
Met evidence standards
Greenwood et al. (1993) randomly assigned schools to intervention or comparison groups. The CWPT program was delivered to one cohort of students for four years while they were in first grade to fourth grade, and outcomes were tracked two years later in sixth grade. For rating purposes, this WWC intervention report focuses on these follow-up findings for 218 sixth-grade students. 1
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. 2
The WWC considers the extent of evidence for CWPT to be small for general reading achievement. No studies that met WWC evidence standards with or without reservations addressed alphabetics, fluency, or comprehension.
2 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.
