“…This is important because mediation refers to dynamic processes that change across time (Selig & Preacher, 2009). Particularly in adolescence, personality (Klimstra, 2013), needbased experiences (Van der Kaap-Deeder, Vansteenkiste, Soenens, & Mabbe, 2017), and symptoms of psychopathology (Larson, Moneta, Richards, & Wilson, 2002) are highly susceptible to change. This raises the question of whether need frustration plays a role at (a) the between-person level (i.e., accounting for between-person differences in self-critical perfectionism and symptoms,) and (b) the within-person level (i.e., accounting for associations between intra-individual change in self-criticism and intra-individual change in symptoms).…”