How to Equate Tests with Little or No Data
EDUCATIONAL TESTING SERVICE PRINCETON NJ
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Standard procedures for equating tests, including those based on item response theory IRT, require item responses from large numbers of examinees. Such data may not be forthcoming for reasons theoretical, political, or practical. Information about items operating characteristics may be available from other sources, however such as content and format skills and strategies required to solve them. This paper shows how, in the IRT framework, collateral information about items can be exploited to augment or even replace examinee responses when linking or equating new tests to established scales. The procedures are illustrated with data from the Pre Professional Skills TestPPST.