Much of the evidential basis for recent policy decisions is grounded in effect size: the standardised mean difference in outcome scores between a study's intervention and comparison groups. This is interpreted as measuring educational influence, importance or effectiveness of the intervention. This article shows this is a category error at two…

In the middle of the 20th century, there was a shift from a skills deficit approach to a positive approach, focused on promoting assets and individual strengths. The role of social-emotional competences became salient. School is a privileged arena for universal and selective prevention interventions that can help pupils in raising their competence…