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ERIC Number: EJ932505
Record Type: Journal
Publication Date: 2011
Pages: 24
Abstractor: As Provided
ISSN: ISSN-0895-7347
DIF Testing with an Empirical-Histogram Approximation of the Latent Density for Each Group
Woods, Carol M.
Applied Measurement in Education, v24 n3 p256-279 2011
This research introduces, illustrates, and tests a variation of IRT-LR-DIF, called EH-DIF-2, in which the latent density for each group is estimated simultaneously with the item parameters as an empirical histogram (EH). IRT-LR-DIF is used to evaluate the degree to which items have different measurement properties for one group of people versus another, irrespective of mean differences on the construct. Usually, the latent distribution is presumed normal for both groups, but results are biased if this assumption is violated. Simulations show that if the latent densities are nonnormal, Type I error and estimates of the item parameters and focal-group mean and SD are more accurate using EH-DIF-2 than standard methods. Free software for carrying out EH-DIF-2 is available on request. (Contains 3 figures, 4 tables, and 3 footnotes.)
Routledge. Available from: Taylor & Francis, Ltd. 325 Chestnut Street Suite 800, Philadelphia, PA 19106. Tel: 800-354-1420; Fax: 215-625-2940; Web site:
Publication Type: Journal Articles; Reports - Research
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A