A Commentary: Single-Case Design Technical Document of the What Works Clearinghouse

The What Works Clearinghouse document on single-case experimental designs is critiqued. Three criticisms are offered. First, between-group experimental concepts and terminology unfortunately seeped into the description of single-case experimental designs; examples and potential negative effects are identified. Second, the document contains a number of critical omissions; four of these are noted. Third, the document contains some “errors” or misconceptions; examples are provided. Despite these criticisms, the document is generally accurate and may become quite useful for individuals reviewing single-case studies when they conduct synthesis of research literature.