School Is Not Healthy
Better educated folks are healthier, but they would be just as healthy with less school:
There is a strong, positive and well-documented correlation between education and health outcomes. There is much less evidence on the extent to which this correlation reflects the causal effect of education on health – the parameter of interest for policy. … Our approach exploits two changes to British compulsory schooling laws that generated sharp differences in educational attainment among individuals born just months apart. … We confirm that the cohorts just affected by these changes completed significantly more education than slightly older cohorts subject to the old laws. However, we find little evidence that this additional education improved health outcomes or changed health behaviors.
There is causation here: *something* is causing both better health outcomes and better access to education. It could be good genes or a good environment.
Perhaps there is a cognitive bias, but there is also a social bias. There is more at stake with questions of causation than correlation, therefore people have more incentive to discover, or claim to have discovered, causal relationships.