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ERIC Number: ED464108
Record Type: Non-Journal
Publication Date: 2002-Apr
Pages: 54
Abstractor: N/A
Reference Count: N/A
The Effect of Large Ability Differences on Type I Error and Power Rates Using SIBTEST and TESTGRAF DIF Detection Procedures.
Gotzmann, Andrea J.
A simulation study was conducted to examine the effect of large ability differences using two differential item functioning (DIF) detection procedures, SIBTEST and TESTGRAF. DIF items are hard to identify when group ability differences are large (A. Gotzmann, C. Vandenberghe, and M. Gierl, 2000; R. Hambleton and H. Rogers, 1989). This problem was investigated in the current study for the SIBTEST and TESTGRAF DIF detection procedures. Four ability differences (0.0, -1.0, -1.5, and -2.0) and 8 sample sizes were manipulated in a simulation study. Type I error and power rates were computed. The SIBTEST Type I error rates were inflated at the larger ability differences. Conversely, the TESTGRAF Type I error rates remained low for most ability differences and sample sizes. The SIBTEST power rates remained high, even with larger ability differences. The TESTGRAF power rates dropped as ability differences were introduced. (Contains 4 figures, 11 tables, and 55 references.) (Author/SLD)
Publication Type: Reports - Research; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A