The impact of school exclusion on mental health and behavioural outcomes: A counterfactual analysis using a large UK-representative study

Background: Research suggests that experiencing school exclusion, including permanent exclusions and suspension is associated with poorer psychosocial outcomes for children; however, this association is vulnerable to confounding. Methods: Using a large UK-based longitudinal study, the Millennium Cohort Study (n=9551 leading to a matched subsample of n=114 treated and 114 controls), and leveraging a wide range of matching variables we used counterfactual analyses to examine the effects of school exclusion at age 11 on emotional problems, conduct problems, ADHD symptoms, peer problems and prosociality at age 14, accounting for measured confounding. Results: We found that young people who experienced school exclusion had significantly worse scores at age 14 on ADHD symptoms, conduct problems, and prosociality. Conclusions: The use of propensity score matching (including matching on prior behavioural problems) strengthens confidence in the notion that the effects are causal. Results point to the need for policies oriented towards reducing school exclusions and ensuring mitigating measures are in place to minimise its impact on those who experience it.