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

Avery: 00:00:00

Today I'm going to tell you the story of one of the earliest and one of

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the greatest data analysts of all time.

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It's a story that had such a big

impact on my life that I actually

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named my consulting company, Snow

Data Science, after this guy.

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His name is John Snow.

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And no, not the guy from Game of

Thrones, but an English physician

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from the mid 1800s who saved a

country from a deadly outbreak of

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cholera using only data analytics.

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London, 1854, and there's a terrifying

disease sweeping the streets.

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Cholera.

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People are dropping like flies

and no one really knows why.

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In fact, over 500 people had died in

this small area in the last 10 days.

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At the time, most people believed that

cholera was spread through the air via

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bad smells and what's called bad air.

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Some people even believed that cholera

was really only coming out of the

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cemeteries from people who had already

previously passed of the disease.

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Basically, no one knew what was

going on in the disease world.

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No one knew how people were getting

sick, They just knew that people were

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getting sick at an alarming rate.

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And with that knowledge, 75 percent of

that part of the city, Soho, fled due

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to fear of contracting the disease.

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Dr.

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Jon Snow was determined to

figure out why these people were

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getting sick and how to fix it.

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You see, Jon was a doctor, and

he had this crazy idea that maybe

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cholera wasn't spread through the

air, but rather through water.

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And to us, that sounds pretty simple.

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But at the time, it was

a revolutionary idea.

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But no one would believe him.

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So he knew he needed data to prove it.

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So John hit the streets.

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He started talking to people

who had gotten sick and asked

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them a series of questions.

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One of which was crucially,

Where are you getting your water?

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And after interviewing dozens

of folks, he looked at his notes

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and realized many had mentioned

getting water from the same well.

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Which was the pump down on Broad Street.

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A curious note, but nothing concrete.

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John realized he needed more.

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And here's where Snow did

something revolutionary and

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thought like a data analyst.

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He created a map of the streets of London

and plotted every cholera case on it.

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Each water pump was highlighted

with a simple black circle, and each

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case of cholera was indicated by a

simple black line stacked on top of

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the other one to represent multiple

contractions at the same residence.

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After constructing the graph, he found

that most of the deaths clustered around

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one pump, the pump on Broad Street.

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This gave him the data driven evidence

that maybe the disease was indeed in

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the water, specifically at that pump.

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This wasn't just a cool visualization that

he made, it was data analytics in action.

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Armed with his data evidence,

he headed to the local officials

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and presented his theory.

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He showed them his map and asked them to

remove the handle of the pump which would

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literally shut water down to that area.

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The government obliged

and shut the pump down.

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And guess what?

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The cholera outbreak

slowed nearly immediately.

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People stopped getting sick.

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People stopped dying.

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And the population of

London returned to the city.

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This analysis didn't only save

lives, it actually changed

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public health care forever.

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Jon Snow's work is considered

one of the earliest examples

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of data analytics in the UK.

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and is still referred to

in pandemics or outbreaks.

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Here are three simple ways that you and

I can be great analysts like Jon Snow.

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Number one, visualize our data.

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We as humans are not very

good at remembering numbers.

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We can only really take a

look at 10 numbers at a time.

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If you don't believe me, try to memorize a

telephone number in less than 10 seconds,

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and if you can, you're above average.

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If you don't believe me,

just try to remember this.

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Number 8 0 1 5 7 2 2 7 7 8 4 3 2 1 7.

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Go ahead and try to repeat that

in the comments down below.

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If you get it, you're above average.

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We as humans are just not good

at dealing with numbers, but

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we are good at visualizing.

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Our eyes are extremely powerful, and

so instead of trying to just understand

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data inside of a notebook or instead

of a spreadsheet, when we visualize

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data, that helps us understand it

better, and that was the key to success.

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To John, figuring out what

was causing this disease.

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Number two, we can storytell with data.

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Notice that John didn't go to the

government and just, you know, show them

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the map or just tell them the theory.

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He combined the two.

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He told a story.

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In fact, they actually asked, well,

what is happening with this green

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area right here and this green

area right here that you see on

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the map, they're not getting sick.

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Why are they not getting sick?

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Even though they're really close

to this well, and he actually

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went and interviewed those people

and found out that one was a bar.

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And they said, quote, no

one drinks water here.

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So those people were actually saved

from cholera by only drinking beer.

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And the second one was actually

a prison where they actually have

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their own well inside of the prison.

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So he was able to illustrate the

full story with the data that was

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able to convince the government

that this was the cause, even though

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everyone thought it was in the air,

that it was actually in the water.

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And number three, another

thing that Jon Snow did very

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well is explain the outliers.

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If you look at the map, you'll

notice that towards the bottom

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and even some other places.

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There are outliers.

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There are people who contracted

cholera that were not close to

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this pump and not using this pump.

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This would actually hurt his

hypothesis, and he knew that.

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So he actually went to those areas to talk

with those people and found out that many

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of them had relatives or they had recently

visited that pump just a couple days ago.

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So the outliers did not

hurt his case, they actually

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ended up supporting his case.

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If you want to be a great analyst

like Jon Snow, go ahead and hit

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subscribe to get future episodes

that will help you get there.