Fitting the two-parameter model to personality data

The Multidimensional Personality Questionnaire (MPQ; Tellegen, 1982) was parameterized using the two-parameter logistic item response model. This entailed assessment of the suitability of personality data for item response analyses, including the assessment of dimensionality, monotonicity of item response, and data-model fit. The latter issue received special emphasis. Similarities and differences between maximum performance and typical performance data are discussed in relation to item response theory. Results suggest that the two-parameter model fits the MPQ data and that researchers engaged in the assessment of normal-range personality processes have much to gain from exploiting item response models. Index terms: item fit, item response theory, Multidimensional Personality Questionnaire, personality measurement, two-parameter model. Within the family of item response models, th