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ERIC Number: ED475704
Record Type: Non-Journal
Publication Date: 2003-Apr
Pages: 32
Abstractor: N/A
Reference Count: N/A
ISBN: N/A
ISSN: N/A
Expected Values and Reliability of Number-Right Scores for IRT Calibrated Items.
Dimitrov, Dimiter M.
This paper provides analytic evaluations of expected (marginal) true-score measures for binary items given their item response theory (IRT) calibration. Under the assumption of normal trait distributions, marginalized true scores, error variance, true score variance, and reliability for norm-referenced and criterion-references interpretations are presented as a function of the item parameters. The proposed formulas have methodological and computational value in bridging concepts of IRT and true score theory. They provide information about the individual contribution of IRT calibrated items to marginal true-score measures for the test and may have valuable applications in test development and analysis. For example, given a bank of IRT calibrated items, one can select binary items to develop a test with known true-score characteristics prior to administering the test (without information about raw scores or trait scores). Calculations with the proposed formulas are easy to perform using basic statistical programs, spreadsheet programs, or even hand-held calculators. Two appendixes contain formula proofs and the Statistical Package for the Social Sciences syntax for evaluation of the marginal true-score measures. (Contains 2 tables and 22 references.) (Author/SLD)
Publication Type: Reports - Descriptive; Speeches/Meeting Papers
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A