An item response theory (IRT) approach to test linking based on summed scores is presented and demonstrated by calibrating a modified 23-item version of the Center for Epidemiologic Studies Depression Scale (CES-D) to the standard 20-item CES-D. Data are from the Depression Patient Outcomes Research Team, II, which used a modified CES-D to measure risk for depression. Responses (N = 1, 120) to items on both the original and modified versions were calibrated simultaneously using F. Samejima's (1964, 1997) graded IRT model. The 2 scales were linked on the basis of derived summed-score-to-IRT-score translation tables. The established cut score of 16 on the standard CES-D corresponded most closely to a summed score of 20 on the modified version. The IRT summed-score approach to test linking is a straightforward, valid, and practical method that can be applied in a variety of situations.
Reprinted with permission from Psychological Assessment, Vol. 12, No. 3, Sept. 2000, pp. 354-359. Copyright © 2000 American Psychological Association, Inc.
Originally published in: Psychological Assessment, Vol. 12, No. 3, Sept. 2000, pp. 354-359.
This report is part of the RAND Corporation Reprint series. The Reprint was a product of the RAND Corporation from 1992 to 2011 that represented previously published journal articles, book chapters, and reports with the permission of the publisher. RAND reprints were formally reviewed in accordance with the publisher's editorial policy and compliant with RAND's rigorous quality assurance standards for quality and objectivity. For select current RAND journal articles, see External Publications.
Permission is given to duplicate this electronic document for personal use only, as long as it is unaltered and complete. Copies may not be duplicated for commercial purposes. Unauthorized posting of RAND PDFs to a non-RAND Web site is prohibited. RAND PDFs are protected under copyright law. For information on reprint and linking permissions, please visit the RAND Permissions page.
The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.