Within and Among Population Item Fit with the Simple Logistic Model

Abstract

The Rasch simple logistic model is used to examine the relative item parameter values of a personality inventory with respect to populations cross classified by sex and country. If the model holds across populations these values should be statistically equivalent. However, while the items conform to the model within each of the populations, half the items show significant discrepancies among the populations. These discrepancies are interpreted both statistically and substantively in terms of main effects and interactions.