ERIC Number: ED481721
Record Type: Non-Journal
Publication Date: 2003-Sep
Reference Count: N/A
On the Use of Collateral Item Response Information To Improve Pretest Item Calibration. LSAC Research Report Series.
Stout, William; Ackerman, Terry; Bolt, Dan; Froelich, Amy Goodwin; Heck, Dan
This study evaluated the practical benefit, if any, of using collateral information for one item type when statistically analyzing pretest items of some other item type. The criterion for evaluation of pretest item calibration accuracy was the reduction achieved by the use of collateral information in the number of test takers that must be administered each pretest item so that its item parameter estimates reach a specified level of accuracy. The proposed methods involved statistical tools that assume one dominant ability being measured on a test and tools that assume two dominant abilities being measured, as has been confirmed to be true for the Law School Admission Test (LSAT). Results from simulation studies demonstrate that there is a practically important amount of improvement in calibrating pretest items of one item type attributable to the use of collateral information from some other type provided only a moderate number of operational items are present for each item type. For purposes of LSAT computerized admission, the high level of ability estimation accuracy for any one item type (because of the more substantial number of items being anticipated) seems to offset any advantage that could be obtained through introducing collateral information from some other item type. (Contains 3 figures and 15 references.) (SLD)
Publication Type: Reports - Research
Education Level: N/A
Authoring Institution: Law School Admission Council, Newtown, PA.