134: The Greatest Data Analyst of All Time (John Snow)

Today I'm going to tell you the story of one of the earliest and one of the greatest data analysts of all time. It's a story that had such a big impact on my life that I actually named my consulting company, Snow Data Science, after this guy. His name is John Snow. And no, not the guy from Game of Thrones, but an English physician from the mid 1800s who saved a country from a deadly outbreak of cholera using only data analytics. London, 1854, and there's a terrifying disease sweeping the streets. Cholera. People are dropping like flies and no one really knows why. In fact, over 500 people had died in this small area in the last 10 days. At the time, most people believed that cholera was spread through the air via bad smells and what's called bad air. Some people even believed that cholera was really only coming out of the cemeteries from people who had already previously passed of the disease. Basically, no one knew what was going on in the disease world. No one knew how people were getting sick, They just knew that people were getting sick at an alarming rate. And with that knowledge, 75 percent of that part of the city, Soho, fled due to fear of contracting the disease. Dr. Jon Snow was determined to figure out why these people were getting sick and how to fix it. You see, Jon was a doctor, and he had this crazy idea that maybe cholera wasn't spread through the air, but rather through water. And to us, that sounds pretty simple. But at the time, it was a revolutionary idea. But no one would believe him. So he knew he needed data to prove it. So John hit the streets. He started talking to people who had gotten sick and asked them a series of questions. One of which was crucially, Where are you getting your water? And after interviewing dozens of folks, he looked at his notes and realized many had mentioned getting water from the same well. Which was the pump down on Broad Street. A curious note, but nothing concrete. John realized he needed more. And here's where Snow did something revolutionary and thought like a data analyst. He created a map of the streets of London and plotted every cholera case on it. Each water pump was highlighted with a simple black circle, and each case of cholera was indicated by a simple black line stacked on top of the other one to represent multiple contractions at the same residence. After constructing the graph, he found that most of the deaths clustered around one pump, the pump on Broad Street. This gave him the data driven evidence that maybe the disease was indeed in the water, specifically at that pump. This wasn't just a cool visualization that he made, it was data analytics in action. Armed with his data evidence, he headed to the local officials and presented his theory. He showed them his map and asked them to remove the handle of the pump which would literally shut water down to that area. The government obliged and shut the pump down. And guess what? The cholera outbreak slowed nearly immediately. People stopped getting sick. People stopped dying. And the population of London returned to the city. This analysis didn't only save lives, it actually changed public health care forever. Jon Snow's work is considered one of the earliest examples of data analytics in the UK. and is still referred to in pandemics or outbreaks. Here are three simple ways that you and I can be great analysts like Jon Snow. Number one, visualize our data. We as humans are not very good at remembering numbers. We can only really take a look at 10 numbers at a time. If you don't believe me, try to memorize a telephone number in less than 10 seconds, and if you can, you're above average. If you don't believe me, just try to remember this. Number 8 0 1 5 7 2 2 7 7 8 4 3 2 1 7. Go ahead and try to repeat that in the comments down below. If you get it, you're above average. We as humans are just not good at dealing with numbers, but we are good at visualizing. Our eyes are extremely powerful, and so instead of trying to just understand data inside of a notebook or instead of a spreadsheet, when we visualize data, that helps us understand it better, and that was the key to success. To John, figuring out what was causing this disease. Number two, we can storytell with data. Notice that John didn't go to the government and just, you know, show them the map or just tell them the theory. He combined the two. He told a story. In fact, they actually asked, well, what is happening with this green area right here and this green area right here that you see on the map, they're not getting sick. Why are they not getting sick? Even though they're really close to this well, and he actually went and interviewed those people and found out that one was a bar. And they said, quote, no one drinks water here. So those people were actually saved from cholera by only drinking beer. And the second one was actually a prison where they actually have their own well inside of the prison. So he was able to illustrate the full story with the data that was able to convince the government that this was the cause, even though everyone thought it was in the air, that it was actually in the water. And number three, another thing that Jon Snow did very well is explain the outliers. If you look at the map, you'll notice that towards the bottom and even some other places. There are outliers. There are people who contracted cholera that were not close to this pump and not using this pump. This would actually hurt his hypothesis, and he knew that. So he actually went to those areas to talk with those people and found out that many of them had relatives or they had recently visited that pump just a couple days ago. So the outliers did not hurt his case, they actually ended up supporting his case. 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