Explanation: Observed mortality rates for cholera are very similar to what would be expected based on a predictive formula derived by William Farr (dotted line).  Farr felt that the statistical relationship supported his miasma theory. Later it was shown that the finding was coincidental, with more access to contaminated drinking water at lower elevations. 

Source: Graph illustrating Farr's elevation theory in Langmuir AD. Bacteriological Review 25, 174, 1961.

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