ERIC Number: EJ928372
Record Type: Journal
Publication Date: 2010
Abstractor: As Provided
Reference Count: 20
Formulation of a DIMTEST Effect Size Measure (DESM) and Evaluation of the DESM Estimator Bias
Seo, Minhee; Roussos, Louis A.
Journal of Educational Measurement, v47 n4 p413-431 Win 2010
DIMTEST is a widely used and studied method for testing the hypothesis of test unidimensionality as represented by local item independence. However, DIMTEST does not report the amount of multidimensionality that exists in data when rejecting its null. To provide more information regarding the degree to which data depart from unidimensionality, a DIMTEST-based Effect Size Measure (DESM) was formulated. In addition to detailing the development of the DESM estimate, the current study describes the theoretical formulation of a DESM parameter. To evaluate the efficacy of the DESM estimator according to test length, sample size, and correlations between dimensions, Monte Carlo simulations were conducted. The results of the simulation study indicated that the DESM estimator converged to its parameter as test length increased, and, as desired, its expected value did not increase with sample size (unlike the DIMTEST statistic in the case of multidimensionality). Also as desired, the standard error of DESM decreased as sample size increased.
Descriptors: Effect Size, Statistical Bias, Computation, Test Length, Sample Size, Correlation, Error of Measurement
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Publication Type: Journal Articles; Reports - Evaluative
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