Person Fit Assessment in the 8th Grade Math Test for TIMSS 2015

The validity of test scores may be compromised because of the presence of aberrant responding behaviors. The presen research applies the  &  person fit statistics to examine the response pattern of TIMSS 8th math test of Australia, Iran, and Republic of Korea. After determining the students with misfitting response pattern, the impact of the inclusion and exclusion of their response on the items parameters estimates has been investigated. The changes in item parameter estimates were found to be significant for some items. In addition, the equivalence of students’ response pattern were determined through   &  person fit statistics, and it was found that there is a consistency between the results of the two statistics. The relationship between the fitting/ misfitting response patterns of the students and their ability has been also studied, and it showed that there is a significant relationship between student’s ability parameter estimation and their response pattern for the  person fit statistic, but for the  person fit statistic, this relationship was not significant.