Tyler Cowen links to a planned mass medical study in Germany.
German scientists are planning the country’s biggest biomedical study. The National Cohort will be an intensive investigation of the health, lifestyle and genetics of 200,000 people, at an estimated cost of €210m over 10 years.
He notes that they don't mention plans to study the efficacy of health care access, but it could still be studied. In fact, it could be better if they don't directly study the effect of health care access and instead merely control for it while looking at other things such as the impact of exercise on health. This way, they will be more likely to throw some variables representing treatment frequency into the regression (At the very least, there is a subgroup of 40,000 receiving more detailed attention) and we can see whether or not the variable is significant or even the right sign. It is better that they don't study it directly because if they studied the impact of health care access directly, they might be more prone to try and jigger the regression until the variable had a sign and significance that fit with their preconception.