ERIC Number: EJ897868
Record Type: Journal
Publication Date: 2010
Abstractor: As Provided
Reference Count: 18
Comparisons among Small Sample Equating Methods in a Common-Item Design
Kim, Sooyeon; Livingston, Samuel A.
Journal of Educational Measurement, v47 n3 p286-298 Fall 2010
Score equating based on small samples of examinees is often inaccurate for the examinee populations. We conducted a series of resampling studies to investigate the accuracy of five methods of equating in a common-item design. The methods were chained equipercentile equating of smoothed distributions, chained linear equating, chained mean equating, the symmetric circle-arc method, and the simplified circle-arc method. Four operational test forms, each containing at least 110 items, were used for the equating, with new-form samples of 100, 50, 25, and 10 examinees and reference-form samples three times as large. Accuracy was described in terms of the root-mean-squared difference (over 1,000 replications) of the sample equatings from the criterion equating. Overall, chained mean equating produced the most accurate results for low scores, but the two circle-arc methods produced the most accurate results, particularly in the upper half of the score distribution. The difference in equating accuracy between the two circle-arc methods was negligible.
Descriptors: Equated Scores, Test Items, Item Sampling, Item Response Theory, Criterion Referenced Tests, Measurement Techniques
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Publication Type: Journal Articles; Reports - Research
Education Level: N/A
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