I’m consistently blown away by what passes for causal analysis in medical journals.
Here’s a cruel and simplified guide to prevailing opinion and practice:
Medical research: Correlation never implies causation.
Epidemiological research: My correlation implies causation, because I controlled for socioeconomic status.
Economics: Confused and conflicted, but sometimes correlation implies causation. If you can find a cool instrumental variable we’ll surely publish you.
I side with the economists on this one.
--Chris Blattman on sloppy causal inference