ERIC Number: ED357059
Record Type: Non-Journal
Publication Date: 1993-Apr
Reference Count: N/A
Item Parameter Estimation Errors and Their Influence on Test Information Functions.
Hambleton, Ronald K.; Jones, Russell W.
Errors in item parameter estimates have a negative impact on the accuracy of item and test information functions. The estimation errors may be random, but because items with higher levels of discriminating power are more likely to be selected for a test, and these items are most apt to contain positive errors, the result is that item information functions and corresponding test information functions tend to be inflated in relation to their true values. The impact of this "capitalization on chance" in item selection on the accuracy of test information functions was investigated, using data from the 1985 administration of the Graduate Management Admissions Test with 2 sample sizes (500 and 2,000). Two factors seemed especially important in determining the size of impact: examinee sample size used in calibrating test items, and the ratio of item bank size to the length of the test constructed using items from the bank. Results from computer simulation clearly indicate that both factors influence test information accuracy, often substantially, with serious problems in accuracy arising when test items were calibrated on modest sample sizes (n=500) and when test item banks were large in relation to the number of items in the tests being constructed. Four figures illustrate the discussion, and three tables present analysis results. (Author/SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Sponsor: Graduate Management Admission Council, Princeton, NJ.
Authoring Institution: N/A
Identifiers - Assessments and Surveys: Graduate Management Admission Test