Answers are grounded in this paper and cite their sources.
Unidimensionality, that is the items in a questionnaire measure only a single construct, is a fundamental requirement for the Rasch model. The paper deals with the detection of unidimensionality making use of principal components analysis of residuals and item fit statistics. Simulated bi-dimensional data sets are analized in order to find regolarities in the behavoiur of these statistical tools. The results are applied to a real database coming from the satisfaction section of the first national survey concerning the social services sector carried out in Italy
No takes yet. Share an insight, caveat, or question.
Brentani et al. (2013) studied this question.