What can 19th Century Cholera Teach us about 6 Sigma?

In 1854 there was an outbreak of Cholera in Central London.  Dr John Snow had a theory that the disease was water borne and so plotted the deaths on a street map to see if he could prove the case.

He showed that the majority of deaths were happening to people who lived near the Broad Street water pump.  Presuming that this was the source of the contamination and to stop the local residents drinking the water, he had the handle of the pump removed, (no doubt this made him very popular).  Lo and behold the Cholera outbreak ended.Service Improvement with Six Sigma

I could argue that Dr Snow was one of the architects of Six Sigma:

  • He defined the problem, stop Cholera deaths
  • He measured the number of deaths
  • He analysed the data, testing his hypothesis by plotting the data on a map
  • He improved the situation, asking people to stop drinking from the pump
  • He controlled the process, taking the handle off (presumably his polite notices and training didn’t work)

And as with all good process improvement there is a deal of debate about whether or not he really fixed the issue.

Although I’d wager Dr Snow had a black belt, I guess it was probably holding his trousers up.  The story shows that there is nothing new under the sun, 6 Sigma is simply a method and a framework.

The real magic, when it comes to service improvement, is to apply some ordered thought and, most importantly, have a go.


  1. There is a lot of debate about the truthfulness of this story.

    Many people arge that the cholera outbreak started to deminish long before the handle of the pump was removed. Others argue that the map wasn’t even drawn up by Dr Snow at all

  2. I think it is a good story

    Also love the Web site, nice to see something focused on service operations.

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