Detecting gender-based differential item functioning on a constructed-response science test

In this study, I explored methods for detecting gender-based differential i tem functioning on a 12th-grade constructed-response (CR) science test admi nistered as part of the National Education Longitudinal Study of 1988 (NELS :88). The primary difficulty encountered with many CR tests is the absence of a reliable and appropriate measure of ability on which to condition. In this study, several combinations of conditioning variables were explored, a nd results were supplemented with evidence from interviews of students who completed the test items. The study revealed that 1 item in particular disp layed a large male advantage and contributed to the gender difference on to tal score. Results were similar to those obtained with the NELS:88 multiple -choice test. In both cases, gender differences were largest on items that involved visualization and called on knowledge acquired outside of school. Implications for users of large-scale assessment results are discussed.