A Nonparametric Approach to the Analysis of Dichotomous Item Responses

An item response theory is discussed which is based on purely ordinal assumptions about the probabilities that people respond positively to items. It is considered as a natural generalization of both Guttman scaling and classical test theory. A distinction is drawn between construction and evaluation of a test (or scale) on the one hand and the use of a test to measure and make decisions about persons' abilities on the other. Techniques to deal with each of these aspects are described and illustrated with examples