Abstract

ASSESSMENT OF WINSTEPS AND BILOG MG3 SOFTWARES IN DETECTING ITEM PARAMETERS IN PHYSICS ACHIEVEMENT TEST

Aliyu, R. Taiwo & Akuche, Ukamaka E

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Abstract This study used Winsteps and Bilog-MG3 software to assess item Parameters of Physics Achievement Test (PAT). A 50 items instrument with a reliability value of 0.82 was developed by the researchers using Classical Test Theory (CTT) principle with a sample of 755 selected through multi-stage sampling technique. The infit and outfit of mean square score (MNSQ) and standardized score (ZSTD) of fitness of Winsteps were used while chi-square and probability values of Bilog-Mg3 were used to assess how well the two software perform in selecting item parameter in the PAT. Eventually, forty-three (43) items whose parameters were known scaled through the Winsteps software and were confirmed to measure the same construct (uni-dimensionality) following the scientific software international (SSI) prescription while 11 items were only recognized by Bilog-MG3 which were not statistically significant and fit into the prescribed model at p< 0.05. This shows that a great disparity occurs between winsteps and Bilog-MG3 software. Therefore, recommendation for the use of winsteps over Bilog-MG3 was made since item parameters show unidimensionality of the test while items of Bilog-MG3 shows variation between subpopulation of test takers. Keywords: Item Response Theory (IRT), Rasch model, 3-PL model, Physics Aptitude Test (PAT),

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