Counterpoint: well into the 1950s, doctors would routinely endorse cigarettes with menthol because they "cleared up your lungs." Even R.A. Fischer, the man who started modern applied statistics, died in 1962 believing that the conclusions drawn from cig studies were at best inconclusive and bad science.

And I'm curious if you could give me examples of a few epi studies that were done before Fisher's time. I was under the impression that he started everything to do with statistics (and that the field didn't really blossom until we could compute the coefficients digitally. Read "The lady tasting tea" for more background on the origins of this stuff).