Every student in America should be required to take a class called, "What Do We Know, and How Do We Know It?" Perhaps if we learned from an early age how we know the things we claim to know, fewer Americans would fall for ridiculous conspiracy theories.
Public health is a field that is widely misunderstood, even by science journalists. That is because epidemiology is an inexact science that is complicated by a large variability in the quality of the data it produces, as well as by its reliance on advanced statistical methods. Let's leave the latter aside and focus on the former. Which epidemiological studies are most reliable and why?
