AN ITEM RESPONSE MODEL WITH SINGLE PEAKED ITEM CHARACTERISTIC CURVES - THE PARELLA MODEL

In this paper an item response model (the PARELLA model) designed spec ifically for the measurement of attitudes and preferences will be intr oduced. In contrast with the item response models currently used (e.g. the Rasch model and, the two and three parameter logistic model) the item characteristic curve is single peaked instead of monotonically in creasing. The model and its properties will be introduced. After this the consequences of these properties for the item writing stage, the e valuation of the concordance of data and model, and the applicability of the model will be discussed. The paper is finished with an example concerning the measurement of change in the attitude in the car-enviro nment issue.