THE PERFORMANCE OF TURKISH AND US STUDENTS ON PISA 2012 MATHEMATICS ITEMS: A DIFFERENTIAL ITEM FUNCTIONING ANALYSIS

This study aimed to understand the differences in probability of answering the mathematics questions on PISA 2012 (Programme for International Student Assessment), of eighth grade students from two different countries: Turkey and the United States. Even though both groups of students from these two countries, theoretically, are on the same trait level on the construct that the mathematics items are assessing, they may answer the questions in different manners. Turkish and American students took the PISA 2012 assessment in Turkish and in English, respectively, and this might affect their responses differently although they have the same skills that the items assess. Through this study, it was revealed the items working differently on these two student groups, through a special analysis method: DIF (Differential Item Functioning). It was used the SIBTEST computerized procedure, see [9], a multidimensional method for detecting the DIF, to reveal the DIF flagged items among all. Based on the SIBTEST procedure, 8 out of 12 items were flagged as DIF items. While 4 of those items are favoring the US students, remain 4 items are favoring the Turkish students. In terms of the construct 12 items measure, these two countries differ from each other by students' probabilities to answer the items correctly. Since the majority of items showed DIF, the next step will be to investigate the reasons of why these items behave differently, especially in terms of the language issue.