To what extent is poor mental health and low educational at- tainment/ drop-out linked? Clearly the association can operate in both directions. From a policy perspective, one would like to know the causal influence of poor mental health on these outcomes. This is notoriously difficult to establish and most research addresses the association rather than the causal impact. The latter can only be es- tablished by experiments (which can be difficult to generalise from) or from techniques that allow one to use “exogenous variation” in mental health to predict its causal impact on later outcomes. Re- cent work by Ding and Lehrer (2007) makes some progress in this direction by.
