“…So far, studies have shown rather inconsistent results regarding different missing data approaches and estimated latent ability variances, reporting overestimation, underestimation, or no bias at all (Custer et al., ; Rose, ; Rose et al., ). Regarding explanatory variables and interest in their relationship with competence, it is also noteworthy that omitted and not‐reached items typically relate to potential explanatory variables such as gender, ethnicity, and other competences (Köhler, Pohl, & Carstensen, ; Koretz, Lewis, Skewes‐Cox, & Burstein, ; Matters & Burnett, ). Glas, Pimentel, and Lamers () investigated the impact of explanatory variables that correlate with missing propensity and competence on the estimation of item difficulty parameters.…”