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An Analysis of the Verbal Scholastic Aptitude Test Using Birnbaum's Three-Parameter Logistic Model SAT

Lord, Frederic M.
Publication Year:
Report Number:
ETS Research Bulletin
Document Type:
Page Count:
Subject/Key Words:
Office of Naval Research, Birnbaum Models, Maximum Likelihood Statistics, Scholastic Aptitude Test (SAT), Test Construction, Weighted Scores


An application of statistical inference technique to practical problems in test design and test evaluation is described, as an illustration of the kinds of results obtainable. Particular attention is given to 1) the information provided by a test at different ability levels, 2) optimum scoring weights for dichotomous items, 3) relative efficiency of different tests and of different scoring methods, 4) branched testing. The successful estimation by maximum likelihood of examinee ability and of the item parameters of Birnbaum's logistic model is briefly described.

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