SENSITIVITY OF MANTEL HAENSZEL MODEL AND RASCH MODEL AS VIEWED FROM SAMPLE SIZE

The aims of this research is to study the sensitivity comparison of Mantel Haenszel and Rasch Model for detection differential item functioning, observed from the sample size. These two differential item functioning (DIF) methods were compared using simulate binary item respon data sets of varying sample size, 200 and 400 examinees were used in the analyses, a detection method of differential item functioning (DIF) based on gender difference. These test conditions were replication 4 times. For both differential item functioning (DIF) detection methods, a test length of 42 items was sufficient for satisfactory differential item functioning (DIF) detection with detection rate increasing as sample size increased. Finding the study revealed that the empirical result show Rasch Model are more sensitive to detection differential item functioning (DIF) than Mantel Haenszel. With reference to findings of this study, it is recomended that the use of Rasch Model in evaluation activities with multiple choice test. For this purpose, it is necessary for every school to have some teachers who are skillfull in analyzing results of test using modern methods (Item Response Theory).

Refinements of Stout’s Procedure for Assessing Latent Trait Unidimensionality

This article provides a detailed investigation of Stout’s statistical procedure (the computer program DIMTEST) for testing the hypothesis that an essentially unidimensional latent trait model fits observed binary item response data from a psychological test. One finding was that DIMTEST may fail to perform as desired in the presence of guessing when coupled with many high-discriminating items. A revision of DIMTEST is proposed to overcome this limitation. Also, an automatic approach is devised to determine the size of the assessment subtests. Further, an adjustment is made on the estimated standard error of the statistic on which DIMTEST depends. These three refinements have led to an improved procedure that is shown in simulation studies to adhere closely to the nominal level of signficance while achieving considerably greater power. Finally, DIMTEST is validated on a selection of real data sets.