AN INVESTIGATION OF PROCEDURES FOR COMPUTERIZED ADAPTIVE TESTING USING THE SUCCESSIVE INTERVALS RASCH MODEL

The major objective of the present study was to evaluate basic procedures for performing computerized adaptive testing (CAT) based on the successive intervals (SI) Rasch model. The SI model is designed for measuring attitudes based on Thurstone's successive intervals concept. The SI model was applied to both simulated and real attitude data sets for which the item response data were polytomous. Using simulated data, such variables as item pool size, method of item selection, and sizes of item dispersion parameters were studied. The results indicated that the CAT procedures performed very well using item pools of either 30 or 61 items; there was excellent recovery of the known attitude trait levels of the simulees, with only about 17 items administered on average during the CATs. For the real data set the CAT procedures also performed very well in terms of number of items administered and accuracy of trait estimation.