Risk, Chance, and Causation

A noted clinical epidemiologist shows how evidence-based medicine can help us understand and assess news about health risks, cures, and treatment "breakthroughs"
The press and other media constantly report news stories about dangerous chemicals in the environment, miracle cures, the safety of therapeutic treatments, and potential cancer-causing agents. But what exactly is actually meant by "increased risk"—should we worry if we are told that we are at twice the risk of developing an illness? And how do we interpret "reduced risk" to properly assess the benefits of noisily touted dietary supplements?