A Tutorial on Cross Wave Measurement Invariance Testing with Item Factor Analysis

The consistency of psychometric properties across waves of data collection provides valuable evidence that scores can be interpreted consistently. Evidence supporting the consistency of psychometric properties can come from using a longitudinal extension of item factor analysis to account for the lack of independence of observation when evaluating the cross-wave properties. In this study, we demonstrate how to conduct and interpret a longitudinal examination of psychometric properties. This demonstration uses data on the Comprehensive Measure of Meaning across two waves of data collection. A simplified, structured set of R syntax for analyses is provided, and all remaining code is freely available in the accompanying Open Science Framework repository.