ERIC Number: ED308204
Record Type: Non-Journal
Publication Date: 1989-Apr-26
Reference Count: N/A
What Combination of Sampling and Equating Methods Works Best? Revised.
Livingston, Samuel A.; And Others
Combinations of five methods of equating test forms and two methods of selecting samples of students for equating were compared for accuracy. The two sampling methods were representative sampling from the population and matching samples on the anchor test score. The equating methods were: (1) the Tucker method; (2) the Levine method; (3) the chained equipercentile method; (4) the frequency estimation; and (5) an item response theory (IRT) method; specifically, the three-parameter logistic model. The tests were the verbal and mathematics sections of the Scholastic Aptitude Test. The criteria for accuracy were measures of agreement with an equivalent-groups equating based on more than 115,000 students taking each form. Much of the inaccuracy in the equatings could be attributed to overall bias. The results for all equating methods in the matched samples were similar to those of the Tucker and frequency estimation methods in the representative samples; these equatings made too small an adjustment for the difference in the difficulty of the test forms. In the representative samples, the chained equipercentile method showed a much smaller bias. The IRT and Levine methods tended to agree with each other and were inconsistent in the direction of their bias. Five tables and four figures present study data. (Author/SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Sponsor: Educational Testing Service, Princeton, NJ.
Authoring Institution: N/A
Identifiers - Assessments and Surveys: SAT (College Admission Test)