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Travel back to 1854 London and see how data visualization saved lives. John Snowβs use of data analytics to fight cholera is a groundbreaking story that still inspires analysts today.
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β TIMESTAMPS
00:24 The Cholera Outbreak in London
01:04 John Snow's Revolutionary Hypothesis
02:58 Lessons for Modern Data Analysts
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00:00:00
Avery: Today I'm going to tell you the
story of one of the earliest and one of
00:00:03
the greatest data analysts of all time.
00:00:05
It's a story that had such a big
impact on my life that I actually
00:00:08
named my consulting company, Snow
Data Science, after this guy.
00:00:12
His name is John Snow.
00:00:14
And no, not the guy from Game of
Thrones, but an English physician
00:00:17
from the mid 1800s who saved a
country from a deadly outbreak of
00:00:21
cholera using only data analytics.
00:00:24
London, 1854, and there's a terrifying
disease sweeping the streets.
00:00:28
Cholera.
00:00:29
People are dropping like flies
and no one really knows why.
00:00:32
In fact, over 500 people had died in
this small area in the last 10 days.
00:00:37
At the time, most people believed that
cholera was spread through the air via
00:00:40
bad smells and what's called bad air.
00:00:43
Some people even believed that cholera
was really only coming out of the
00:00:46
cemeteries from people who had already
previously passed of the disease.
00:00:49
Basically, no one knew what was
going on in the disease world.
00:00:52
No one knew how people were getting
sick, They just knew that people were
00:00:55
getting sick at an alarming rate.
00:00:57
And with that knowledge, 75 percent of
that part of the city, Soho, fled due
00:01:02
to fear of contracting the disease.
00:01:04
Dr.
00:01:05
Jon Snow was determined to
figure out why these people were
00:01:08
getting sick and how to fix it.
00:01:09
You see, Jon was a doctor, and
he had this crazy idea that maybe
00:01:13
cholera wasn't spread through the
air, but rather through water.
00:01:17
And to us, that sounds pretty simple.
00:01:18
But at the time, it was
a revolutionary idea.
00:01:21
But no one would believe him.
00:01:23
So he knew he needed data to prove it.
00:01:25
So John hit the streets.
00:01:26
He started talking to people
who had gotten sick and asked
00:01:29
them a series of questions.
00:01:30
One of which was crucially,
Where are you getting your water?
00:01:34
And after interviewing dozens
of folks, he looked at his notes
00:01:37
and realized many had mentioned
getting water from the same well.
00:01:40
Which was the pump down on Broad Street.
00:01:43
A curious note, but nothing concrete.
00:01:45
John realized he needed more.
00:01:47
And here's where Snow did
something revolutionary and
00:01:50
thought like a data analyst.
00:01:51
He created a map of the streets of London
and plotted every cholera case on it.
00:01:56
Each water pump was highlighted
with a simple black circle, and each
00:01:59
case of cholera was indicated by a
simple black line stacked on top of
00:02:03
the other one to represent multiple
contractions at the same residence.
00:02:06
After constructing the graph, he found
that most of the deaths clustered around
00:02:10
one pump, the pump on Broad Street.
00:02:13
This gave him the data driven evidence
that maybe the disease was indeed in
00:02:17
the water, specifically at that pump.
00:02:19
This wasn't just a cool visualization that
he made, it was data analytics in action.
00:02:24
Armed with his data evidence,
he headed to the local officials
00:02:27
and presented his theory.
00:02:28
He showed them his map and asked them to
remove the handle of the pump which would
00:02:32
literally shut water down to that area.
00:02:34
The government obliged
and shut the pump down.
00:02:37
And guess what?
00:02:38
The cholera outbreak
slowed nearly immediately.
00:02:41
People stopped getting sick.
00:02:43
People stopped dying.
00:02:44
And the population of
London returned to the city.
00:02:46
This analysis didn't only save
lives, it actually changed
00:02:50
public health care forever.
00:02:51
Jon Snow's work is considered
one of the earliest examples
00:02:54
of data analytics in the UK.
00:02:55
and is still referred to
in pandemics or outbreaks.
00:02:58
Here are three simple ways that you and
I can be great analysts like Jon Snow.
00:03:03
Number one, visualize our data.
00:03:05
We as humans are not very
good at remembering numbers.
00:03:08
We can only really take a
look at 10 numbers at a time.
00:03:11
If you don't believe me, try to memorize a
telephone number in less than 10 seconds,
00:03:15
and if you can, you're above average.
00:03:18
If you don't believe me,
just try to remember this.
00:03:20
Number 8 0 1 5 7 2 2 7 7 8 4 3 2 1 7.
00:03:26
Go ahead and try to repeat that
in the comments down below.
00:03:28
If you get it, you're above average.
00:03:30
We as humans are just not good
at dealing with numbers, but
00:03:33
we are good at visualizing.
00:03:35
Our eyes are extremely powerful, and
so instead of trying to just understand
00:03:39
data inside of a notebook or instead
of a spreadsheet, when we visualize
00:03:42
data, that helps us understand it
better, and that was the key to success.
00:03:45
To John, figuring out what
was causing this disease.
00:03:48
Number two, we can storytell with data.
00:03:51
Notice that John didn't go to the
government and just, you know, show them
00:03:54
the map or just tell them the theory.
00:03:56
He combined the two.
00:03:57
He told a story.
00:03:59
In fact, they actually asked, well,
what is happening with this green
00:04:03
area right here and this green
area right here that you see on
00:04:06
the map, they're not getting sick.
00:04:08
Why are they not getting sick?
00:04:09
Even though they're really close
to this well, and he actually
00:04:12
went and interviewed those people
and found out that one was a bar.
00:04:15
And they said, quote, no
one drinks water here.
00:04:18
So those people were actually saved
from cholera by only drinking beer.
00:04:22
And the second one was actually
a prison where they actually have
00:04:24
their own well inside of the prison.
00:04:27
So he was able to illustrate the
full story with the data that was
00:04:30
able to convince the government
that this was the cause, even though
00:04:33
everyone thought it was in the air,
that it was actually in the water.
00:04:36
And number three, another
thing that Jon Snow did very
00:04:39
well is explain the outliers.
00:04:40
If you look at the map, you'll
notice that towards the bottom
00:04:43
and even some other places.
00:04:44
There are outliers.
00:04:45
There are people who contracted
cholera that were not close to
00:04:48
this pump and not using this pump.
00:04:50
This would actually hurt his
hypothesis, and he knew that.
00:04:53
So he actually went to those areas to talk
with those people and found out that many
00:04:57
of them had relatives or they had recently
visited that pump just a couple days ago.
00:05:02
So the outliers did not
hurt his case, they actually
00:05:04
ended up supporting his case.
00:05:06
If you want to be a great analyst
like Jon Snow, go ahead and hit
00:05:09
subscribe to get future episodes
that will help you get there.
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