THE IMPACT OF ITEM DELETION ON EQUATING CONVERSIONS AND REPORTED SCORE DISTRIBUTIONS

Abstract

A formal analysis of the effects of item deletion on equating/scaling functions and reported score distributions is presented. There are two components of the present analysis: analytical and empirical. The analytical decomposition demonstrates how the effects of item characteristics, test properties, individual examinee responses, and rounding rules combine to produce the item deletion effect on the equating/scaling function and candidate scores, In addition to demonstrating how the deleted item's psychometric characteristics can affect the equating function, the analytical component of the report examines the effects of not scoring versus scoring all options correct, the effects of re‐equating versus not re‐equating, and the interaction between the decision to re‐equate or to not re‐equate and the scoring option chosen for the flawed item. The empirical portion of the report uses data from the May 1982 administration of the SA T, which contained the circles item, to illustrate the effects of item deletion on reported score distributions and equating functions. The empirical data verify what the analytical decomposition predicts.