Psychometric Properties of Raw and Scale Scores on Mixed-Format Tests

Abstract

This paper illustrates that the psychometric properties of scores and scales that are used with mixed-format educational tests can impact the use and interpretation of the scores that are reported to examinees. Psychometric properties that include reliability and conditional standard errors of measurement are considered in this paper. The focus is on mixed-format tests in situations for which raw scores are integer-weighted sums of item scores. Four associated real-data examples include (a) effects of weights associated with each item type on reliability, (b) comparison of psychometric properties of different scale scores, (c) evaluation of the equity property of equating, and (d) comparison of the use of unidimensional and multidimensional procedures for evaluating psychometric properties. Throughout the paper, and especially in the conclusion section, the examples are related to issues associated with test interpretation and test use.