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Estimating Conditional Distributions of Scores on an Alternate Form of a Test

Livingston, Samuel A.; Chen, Haiwen (Henry)
Publication Year:
Report Number:
ETS Research Report
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Subject/Key Words:
Reliability, Score Distributions, Consistency


Quantitative information about test score reliability can be presented in terms of the distribution of equated scores on an alternate form of the test for test takers with a given score on the form taken. In this paper, we describe a procedure for estimating that distribution, for any specified score on the test form taken, by estimating the joint distribution of equated scores on two forms of the test. The procedure requires as input the score distribution and the reliability coefficient, estimated for the test-taker population. In tryouts, the procedure performed well for score distributions like those commonly encountered in large-scale testing situations.

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