Mokken, R.J. ( 1971 ). A theory and procedure of scale analysis. The Hague, The Netherlands: Mouton.
2.
Mokken, R.J., & Lewis, C. (1982). A nonparametric approach to the analysis of dichotomous item responses. Applied Psychological Measurement, 6, 417-430.
3.
Sytsma, K., & Molenaar, I.W. (1987). Reliability of test scores in nonparametric item response theory. Psychometrika, 52, 79-97.
