This paper describes an approach to item analysis that is based on the estimation of a set of response curves for each item. The response curves show, at a glance, the difficulty and the discriminating power of the item and the popularity of each distractor, at any level of the criterion variable (e.g., total score). The curves are estimated by…

A visual display is introduced that enables one to compare the predictive validities of all possible non-negatively weighted sums of two predictors. This two-predictor validity curve assesses the level of predictability of a criterion from composites of two predictors. Derivations are presented for the general case. For illustrative purposes, the…