Browsing by Author "Lewis, Charles"
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Item Computerized mastery testing with nonequivalent testlets(1992) Sheehan, Kathleen; Lewis, CharlesA procedure for determining the effect of testlet nonequivalence on the operating characteristics of a testlet-based computerized mastery test (CMT) is introduced. The procedure involves estimating the CMT decision rule twice-once with testlets treated as equivalent and once with testlets treated as nonequivalent. In the equivalent testlet mode, the likelihood functions (LFS) estimated for specific number-correct (NC) scores are assumed to be constant across testlets and a single set of cutscores is estimated for all testlets. In the nonequivalent testlet mode, the LFS estimated for specific NC scores are allowed to vary from one testlet to another and a different set of cutscores is estimated for each permutation of testlet presentation order. Small differences between the estimated operating characteristics of the equivalent testlet decision rule and the nonequivalent testlet decision rule indicate that the assumption of equivalent testlets was warranted. This procedure is demonstrated with data from the Architect Registration Examination. Index terms: Bayesian methods, computerized mastery testing, decision theory, item response theory, test equivalence, testlets.Item A nonparameteric approach to the analysis of dichotomous item responses(1982) Mokken, Robert J.; Lewis, CharlesAn 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.Item Rejoinder to "The Mokken scale: A critical discussion."(1986) Mokken, Robert J.; Lewis, Charles; Sijtsma, KlaasThe nonparametric approach to constructing and evaluating tests based on binary items proposed by Mokken has been criticized by Roskam, van den Wollenberg, and Jansen. It is contended that their arguments misrepresent the objectives of this approach, that their criticisms of the role of the H coefficient in the procedures are irrelevant or erroneous, and that they fail to distinguish the inherent requirements (and limitations) of general nonparametric models and procedures from those of parametric ones. It is concluded that Mokken’s procedures provide a useful tool for researchers in the social sciences who wish to construct and evaluate tests for measuring theoretically meaningful latent traits while avoiding the strong parametric assumptions of traditional item response theory.Item Using Bayesian decision theory to design a computerized mastery test(1990) Lewis, Charles; Sheehan, KathleenA theoretical framework for mastery testing based on item response theory and Bayesian decision theory is described. The idea of sequential testing is developed, with the goal of providing shorter tests for individuals who have clearly mastered (or clearly not mastered) a given subject and longer tests for those individuals for whom the mastery decision is not as clear-cut. In a simulated application of the approach to a professional certification examination, it is shown that average test lengths can be reduced by half without sacrificing classification accuracy. Index terms: Bayesian decision theory, computerized mastery testing, item response theory, sequential testing, variable-length tests.