The purpose of this research was to analyze the differential item functioning (DIF) and the differential test functioning (DTF) of scholastic aptitude test (SWUSAT) for groups of students and classified by gender. The data used in this research is the secondary data from Srinakharinwirot University Scholastic Aptitude Test year 2011 and 2013. SWUSAT test consists of 4 subjects and 10 tests. There are verbal test, number test, reasoning test and spatial test. The data analysis was analyzed in 2 steps. First to analyzing descriptive statistics. Second, to analyzed differential item functioning and differential test functioning by using the DIFAS program.

Results

The results of DIF and DTF analysis for all 10 tests in year 2011. Gender was the characteristic that found DIF all 10 tests. The percentage of item number that found DIF between 10% - 46.67%. For Differential test functioning (DTF), There are 8 tests that have small level.  The results of DIF and DTF analysis for all 10 tests in year 2013. Gender was the characteristic that found DIF all 10 tests. The percentage of item number that found DIF between 6.67% - 60%. For Differential test functioning (DTF), there are 8 tests that have small level.