Show Me
Your Data

An intro to charts and data visualization


The Plan:

How do I best show my data?

How to spot different chart types in the wild

How to make them!

Same data, different encoding

Paul Reiman

How important is accuracy?

Gabriela Plucinska, based on a 1984 Cleveland & McGill study

What are you trying to show?

Encoding matters!


Bar vs Line

Bar Charts

Very accurate

Distinct/categorical data

Good for making comparisons

The bread and butter of data viz

Pew Research Center

But bar charts can be powerful too!

New York Times

Or appear in unexpected forms


Line Charts

Continuous data

Good for showing trends

Line charts are good for showing data over time

New York Times

Whether that's telling one story...

New York Times

...or making comparisons


...or showing proportions

Pew Research Center

Pie Charts

Good for showing parts of a whole

Use sparingly

The best pie chart

The worst pie chart

Ok, maybe this is the worst one

The more slices, the harder to read

Walter Crosby Eells 1926 study, via Manuel Lima


Good for showing relationships

Trickier to read

Scatterplots can show a lot of data at once

New York Times

They can show inequality

New York Times

They don't have to be boring!

New York Times


Good for when geography is important

Beware the population map!

Choropleth map: typical election map

Washington Post

Choropleth map with smaller geographies

New York Times

Cartogram: when geography is less important

New York Times

Cartogram: quickly make comparisons


Symbol map: to show specific places

Washington Post

Did you just make a population map?


Totals vs. per capita

Washington Post

Ok, how do I make some?


Free online tool for making charts and maps

They have tons of tutorials for all kinds of chart types

I made a few also:

What next?

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