Evaluating the use of exploratory factor analysis in developmental disability psychological research.

Exploratory factor analysis (EFA) is a widely used but poorly understood statistical procedure. This paper described EFA and its methodological variations. Then, key methodological variations were used to evaluate EFA usage over a 10-year period in five leading developmental disabilities journals. Sixty-six studies were located and evaluated on multiple procedural variations. Only 35% (n = 23) of studies used EFA; principal components analysis was the model used most often (n = 40, 61%). Orthogonal rotation was used most often (n = 39, 59%). A large portion of studies ran analyses with a subject: item ratio larger than 5:1 (n = 49, 74%). Most researchers employed multiple criteria for retaining factors (n = 45, 68%). Overall, results indicated that published recommendations and guidelines for the use of EFA are largely ignored.