Applying Multigroup Confirmatory Factor Models for Continuous Outcomes to Likert Scale Data Complicates Meaningful Group Comparisons

Treating Likert rating scale data as continuous outcomes in confirmatory factor analysis violates the assumption of multivariate normality. Given certain requirements pertaining to the number of categories, skewness, size of the factor loadings, and so forth, it seems nevertheless possible to recover true parameter values if the data stem from a single homogeneous population. It is shown that, in a multigroup context, an analysis of Likert data under the assumption of multivariate normality may distort the factor structure differently across groups. In that case, investigations of measurement invariance (MI), which are necessary for meaningful group comparisons, are problematic. Analyzing subscale scores computed from Likert items does not seem to solve the problem.