Confirmatory measurement modeling and longitudinal invariance of the CompACT-15: A short-form assessment of psychological flexibility.

The Comprehensive Assessment of Acceptance and Commitment Therapy Processes (CompACT; Francis et al., 2016) is a recently developed measure of psychological flexibility (PF) possessing several advantages over other measures of PF, including multidimensional assessment and relative brevity. Unfortunately, previous psychometric evaluations of the CompACT have been limited by their use of exploratory factor analysis to assess dimensionality, coefficient α to assess reliability, and a lack of attention to measurement equivalence in assessing change over time. The present study used confirmatory factor analysis (CFA) and item factor analysis (IFA) to examine the dimensionality, factor-specific reliability, longitudinal measurement invariance, and construct validity of the CompACT items in a longitudinal online sample of U.S. adults (