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A bar chart uses rectangular bars to make numerical comparisons between independent categories of data. The larger the rectangle, the greater the value represented.
Vocabulary
- Bar chart: a chart that uses rectangular bars to make numerical comparisons between independent categories of data. The larger the rectangle, the greater the value represented.
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[MUSIC]
0:00
When learning about data visualization,
it's easy to get overwhelmed by
0:09
the number of methods available for
presenting your data.
0:14
A website called the Data Visualisation
Catalogue offers descriptions and
0:17
examples of 50 different
visualization methods.
0:23
And there may be other
visualizations not listed here.
0:27
But memorizing a massive list of
visualizations isn't a good use of
0:31
your time.
0:35
Over the next few stages, we're
going to cover some of the most
0:37
common methods for
presenting data.
0:40
In most cases, the charts covered
here will serve your needs.
0:42
If not, you can always do more
research in finding the ideal
0:46
visualization to tell
your data's story.
0:51
And when in doubt,
this quote from computer scientist
0:54
Ben Shneiderman should help you.
0:58
The purpose of visualization is insight,
not pictures.
1:00
In other words, data visualization
isn't about creating pretty graphics.
1:04
It's about providing meaningful
context to your data, so
1:10
users can gain insight and make decisions.
1:14
With that in mind, let's take a look
at our first type of visualization,
1:17
the bar chart.
1:22
A bar chart uses rectangular bars
to make numerical comparisons
1:24
between independent categories of data.
1:29
The larger the rectangle,
the greater the value represented.
1:32
How do bar charts tell stories?
1:36
The chart on screen compares visitors to
selected national parks in America for
1:39
the year 2018.
1:44
The y axis is labeled to
represent millions of visitors,
1:46
starting at 0 and
growing as high as 2.2 million visitors.
1:51
The x axis is labeled to represent
different national parks.
1:56
We can glance at this chart and
make a quick comparison and
2:00
determine that Cuyahoga Valley and
2:04
Gateway Arch were more popular in 2018
than the other national parks listed.
2:07
In most cases,
you'll want to be careful to start
2:13
numbering your y axis at
zero as this chart has done.
2:17
Otherwise the data looks distorted.
2:21
Here's the same chart with the y
axis beginning at 1.4 million.
2:23
Now it looks like Cuyahoga Valley and
Gateway Arch were massively more popular,
2:29
which is pretty misleading.
2:34
When presenting data on a bar or
column chart,
2:37
make sure you're not working with
an overwhelming number of categories.
2:40
This chart demonstrating the number
of cat owning households in America
2:45
compares all 50 states,
which is a lot of information at once.
2:50
I can't confidently say
whether Delaware or
2:54
Vermont has a greater number of cat owners
since the rectangles are so far apart.
2:57
This chart also might have told a more
impactful story with the bars sorted
3:04
from tallest to shortest,
rather than in alphabetical order.
3:08
Use extreme caution when
applying 3D effects to any chart.
3:14
Here's a bar chart demonstrating
the number of female and
3:18
male passengers riding on
the Titanic when it sank in 1912.
3:22
When presented as a 3D chart,
the numbers of passengers riding
3:26
in each class become much harder
to compare to one another.
3:32
Bar charts can be oriented horizontally or
vertically.
3:37
Some practitioners of data visualization
refer to vertically oriented
3:41
charts as column charts to distinguish
them from horizontal bar charts,
3:46
though this terminology isn't universal.
3:51
For the most part, the two orientations
can be used interchangeably.
3:54
However, the horizontal
bar chart allows room for
3:59
longer category labels,
while the vertical column chart does
4:03
a better job of visualizing
numbers that fall below zero.
4:08
In our next video,
we'll take a look at the histogram,
4:12
a visualization that looks a bit like a
bar chart but serves a different purpose.
4:15
Stay tuned.
4:20
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