The difficulties in comparing profile variability (a measure of test scatter) are briefly discussed and the limitations of current techniques pointed out. Test scatter is defined as individual variation in test scores between or within various psychological and educational tests. Currently, no statistical technique for the comparison of profile…

This research investigated the use of the Rasch simple logistic model in obtaining test-free ability estimates. Raw-score ability estimates were influenced by the difficulty of the items used in measurement but Rasch ability estimates were relatively independent of the item difficulty. (Author/CTM)

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…

Monte Carlo simulation procedures were used to study the psychometric characteristics of two two-stage adaptive tests and a conventional "peaked" ability test. Results showed that scores yielded by both two-stage tests better reflected the normal distribution of underlying ability. Ability estimates yielded by one of the two stage tests…