ERIC Number: ED421550
Record Type: Non-Journal
Publication Date: 1998
Reference Count: N/A
Modification Indices for the 2PL and the Nominal Response Model. Research Report 98-04.
Glas, Cees A. W.
In this paper it is shown that various violations of the two parameter logistic (2PL) model can be evaluated using the Lagrange multiplier test (J. Aitchison and S. Silvey, 1958) or the equivalent difference score test. The tests focus on violation of local stochastic independence and insufficient capture of the form of the item characteristic curves. Primarily, the tests are item-oriented diagnostic tools, but taken together, they also serve the purpose of evaluation of global model fit. A useful feature of Lagrange multiplier statistics is that they are evaluated using maximum likelihood estimates of the null model only; that is, the parameters of alternative models need not be estimated. As numerical examples, an application on real data and some power studies are presented. (Contains 1 figure, 9 tables, and 33 references.) (Author/SLD)
Descriptors: Foreign Countries, Goodness of Fit, Item Response Theory, Maximum Likelihood Statistics, Test Items
Faculty of Educational Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Publication Type: Reports - Evaluative
Education Level: N/A
Authoring Institution: Twente Univ., Enschede (Netherlands). Faculty of Educational Science and Technology.