A comparative study of the dimensionality of the self-concealment scale using principal components analysis and Mokken scale analysis.

We discuss and contrast 2 methods for investigating the dimensionality of data from tests and questionnaires: the popular principal components analysis (PCA) and the more recent Mokken scale analysis (MSA; Mokken, 1971). First, we discuss the theoretical similarities and differences between both methods. Then, we use both methods to analyze data collected by means of Larson and Chastain's (1990) Self-Concealment Scale (SCS). We present the different results and highlight the instances in which the methods complement one another so as to obtain a stronger result than would be obtained using only 1 method. Finally, we discuss the implications of the results for the dimensionality of the SCS and provide recommendations for both the further development of the SCS and the future use of PCA and MSA in personality research.