Inconsistencies in DIF Detection for Sub-Groups in Heterogeneous Language Groups

Diversity and heterogeneity among language groups have been well documented. Yet most fairness research that focuses on measurement comparability considers linguistic minority students such as English language learners (ELLs) or Francophone students living in minority contexts in Canada as a single group. Our focus in this research is to examine the degree to which measurement comparability, as indicated by differential item functioning (DIF), is consistent for sub-groups among linguistic minority Francophone students in Canada. The findings suggest that the linguistic minority Francophone students who speak French at home and those who do not speak French at home should not be grouped together for investigating measurement comparability or for examining performance gaps. We identified a great degree of differences in DIF identification with a consistency of 7-10% in DIF identification in the separate analyses for the two groups. The findings highlight methodological problems with investigating fairness for diverse linguistic groups that are treated as a single group.