Not until the twentieth century did the idea of randomized trial experiments, careful measurement, and statistical power take hold. “Is the application of the numerical method to the subject-matter of medicine a trivial and time-wasting ingenuity as some hold, or is it an important stage in the development of our art, as others proclaim it,” the Lancet asked in 1921. The British statistician Austin Bradford Hill responded emphatically that it was the latter, and laid out a template for modern medical investigation.
