Confirmatory factor analysis. Recommendations for unweighted least squares method related to Chi-Square and RMSEA

Abstract

In order to obtain evidences about construct validity through Confirmatory Factor Analysis in Social Sciences, working with skewed ordinal variables has been usual. In this simulation study the performance of Unweighted Least Squares (ULS) method in Likert scales according to Likelihood Ratio Test (C2) and RMSEA indices is analysed through Type I error. For this purpose, four experimental factors have been manipulated: the number of factors or dimensions (2, 3, 4, 5, 6), the number of response points (3, 4, 5, 6), the degree of skewness of the responses distribution (symmetric, moderately and severely asymmetric) and the sample size (100, 150, 250, 450, 650, 850) of the simulated models. According to the main results, C2 index always shows a bigger Type I error than RMSEA, regardless of the experimental factors analysed. Finally, different action alternatives are discussed and future research lines are presented.