Test Theory with Qualitative and Quantitative Latent Variables

Abstract

Latent trait models and latent class models can be considered as two alternative, mutually complementary approaches to analyzing data obtained from tests and questionnaires. Data of this type are characterized by the fact that a larger number of manifest variables, that is, the items, are observed and that all manifest variables refer to the same aspect of personality of the individuals and are designed to measure it. The ultimate aim of a test analysis is to make comparative statements about the individuals by representing them on a scale, that is, by allocating them values of a latent variable. In the case of latent trait models, this latent person variable is quantitative, the persons are represented on a metric scale. In the case of latent class models the latent person variable is qualitative, the persons are mapped into a set of categories or classes.