The Story of John Snow and How He Saved Countless Lives

Randomized control trials (RCTs) have long been considered the gold standard for determining the effectiveness of a drug, surgery, or other medical intervention. But observational studies, although long regarded as second-rate compared to RCTs, have contributed invaluable information to the medical sciences. Indeed, analyses of RCTs compared to observational studies have concluded that well-run observational studies are comparable. I will explain RCTs and observational studies later in this post, but first, I want to tell the story of John Snow and how he used his powers of observation to lower worldwide death rates, perhaps more than anyone in history.