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ERIC Number: EJ1111388
Record Type: Journal
Publication Date: 2006-Nov
Pages: 47
Abstractor: As Provided
ISSN: EISSN-2330-8516
Choice of Anchor Test in Equating. Research Report. ETS RR-06-35
Sinharay, Sandip; Holland, Paul
ETS Research Report Series, Nov 2006
It is a widely held belief that anchor tests should be miniature versions (i.e., minitests), with respect to content and statistical characteristics of the tests being equated. This paper examines the foundations for this belief. It examines the requirement of statistical representativeness of anchor tests that are content representative. The equating performance of several types of anchor tests, including those having statistical characteristics that differ from those of the tests being equated, is examined through several simulation studies and a real data example. Anchor tests with a spread of item difficulties less than that of a total test seem to perform as well as a minitest with respect to equating bias and equating standard error. Hence, the results demonstrate that requiring an anchor test to mimic the statistical characteristics of the total test may be too restrictive and need not be optimal. As a side benefit, this paper also provides a comparison of the equating performance of post-stratification equating and chain equipercentile equating.
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Publication Type: Journal Articles; Reports - Research; Numerical/Quantitative Data
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A
Grant or Contract Numbers: N/A