Background: This study examined differences in students' time spent in physical activity (PA) across secondary schools in rural, suburban, and urban environments and identified the environment-level factors associated with these between school differences in students' PA. Methods: Multilevel linear regression analyses were used to examine the…

The present study introduces and demonstrates a new methodology for item and test bias studies: "moderated differential item functioning (DIF)." This technique expands the DIF methodology to incorporate contextual and sociological variables as moderating or mediating effects of the DIF. Specifically, this paper explores differential…