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ERIC Number: ED400311
Record Type: Non-Journal
Publication Date: 1996-Apr
Pages: 25
Abstractor: N/A
Reference Count: N/A
Examining the Sources and Effects of Local Dependence.
Thompson, Tony D.; Pommerich, Mary
Conditional item independence, also known as local independence, is necessary for the accurate estimation of item parameters within item response theory (IRT). Given that the condition of local independence will be violated to at least some degree when unidimensional models are used to represent multidimensional data, it is important to study the robustness of the unidimensional IRT models under these conditions. This paper identifies the sources and effects of local dependence for a national standardized achievement English test. The G-squared index and NOHARM (C. Fraser, 1988) residual analysis were selected as the most appropriate measures of evaluating the sources of local dependence. Results of the two analyses show that the last 20 items of the English test contain local dependence, which is primarily a speededness effect. It is also apparent that the item parameter estimates of the three-parameter model were affected by this dependence. Results are similar to those of previous research in that local dependence was found to affect estimated information and reliability when the test was scored polytomously. (Contains 6 tables, 6 figures, and 20 references.) (SLD)
Publication Type: Reports - Evaluative; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A