“…These studies can be grouped by the analytic strategy they applied. The first group of studies examined mean-level differences in self-concepts in relation to achievement differences by splitting the achievement continuum into discrete groups (i.e., low-, average-, and high-achieving students) using planned contrasts, ANOVAs, or multigroup comparisons in structural equation models (Möller & Pohlmann, 2010;Prast, Van de Weijer-Bergsma, Mioc ˇevic ´, Kroesbergen, & Van Luit, 2018;Schurtz, Pfost, & Artelt, 2014;Van der Beek, Van der Ven, Kroesbergen, & Leseman, 2017). The second group of studies investigated the relation between achievement and self-concept by using polynomial regression analyses (Marsh, 2004;Marsh & Rowe, 1996).…”