The model for educational measurement developed by George Rasch, a Danish psychometrician, is reviewed and its application to occupational educational testing discussed. The Rasch model is an adaptation from the theory of latent trait analysis. According to it, answering an item correctly is a function of the difficulty of the item and the ability…

How accurately ability is estimated when the test model does not fit the data is considered. To address this question, this study investigated the accuracy of the maximum likelihood estimator of ability for the one-, two- and three-parameter logistic (PL) models. The models were fitted into generated item characteristic curves derived from the…

Statistical procedures are presented for determining ordinal and disordinal aptitude-treatment interactions with linear and curvilinear data. The paper presents a method for testing the homogeneity of group regressions for a single aptitude and provides models for expanding this test to linear and curvilinear regression planes. Procedures are…

It is now widely agreed that current ability measures reflect a complex interaction of environment with genetic potential. This leads to a basic measurement problem since persons with the same measured ability may vary widely in potential due to non-equivalent learning opportunities. The purpose of this paper is to present a model which may hold…