John Snow, Asiatic Cholera and the inductive-deductive method - republished

Lecture 12: further explanation of the Golden Square outbreak

The Snow series is an educational course. We hope you will recognise our efforts by donating to TTE or becoming a paying subscriber, as writing the series took a lot of time and effort.

Last week, we examined the Broad Street outbreak. Looking at the Broad Street map, we are struck by the relationship between the location of the pump and the cluster of deaths: the closer to the pump, the higher the death toll. 

This fact fits Snow’s theory well. Fetching water is heavy work, and it is only natural that you would draw water from your closest source. There was little chance of ascertainment bias as Snow had managed to identify most of those who died of cholera regardless of where they died, although he was well aware that some might have remained unidentified.

As we shall see further on, Snow was slowly disproving alternative explanations for the communication of cholera through his industry and hard work.

So, the map links exposure (con…