This study investigated the Outcome Questionnaire's (OQ-45) factor structure and demonstrated the use of factor mixture modeling (FMM) for the purpose of score validation. OQ-45 scores did not fit the one-class, one- and three-factor models. Use of FMM to identify a two-class model is detailed. Implications for OQ-45 users are provided. (Contains…

In this article, the authors present a multilevel (or hierarchical linear) model that illustrates issues in the application of the model to data from meta-analytic studies. In doing so, several issues are discussed that typically arise in the course of a meta-analysis. These include the presence of non-zero between-study variability, how multiple…