“…Another element that could be hidden by estimating the average effect of training on a labor market or national economy is the heterogeneous response to the intervention. In this case, there is a mix‐up between which outcomes were possible to produce by specific training characteristics (e.g., timing, intensity, nature of the skill, follow‐up procedures) and some premarket characteristics that can play a role in the observed outcome (e.g., discrimination, motivations, cognitive abilities, and prior skill development, among others) (Carneiro et al, 2005; Didier, 2021b; Saar et al, 2014; Van der Mee, 2011).…”