THE CHART CLINIC

CHARTS NEED HELP.

WON’T YOU HELP THE CHARTS?

LAUREL HYATT, 9 JUNE 2013

© Laurel Hyatt

BAR CHART DO’S AND DON’TS

Do:

• Make the Y axis 0 if possible

• Show scales (such as years) in even increments

Don’t:

• Use more than about 10 bars per chart

• Use more than about three sections in stacked chart

• Be too precise with number labels

• Turn a time series into line chart if years are missing

WHEN A BAR CHART SHOULD BE SOMETHING ELSE

When you have… Instead of a bar chart, you should use..

Too little data Text

Too much or very precise data Table

Even-year time series Line chart

Parts of a whole (percentages add to 100%)

Pie chart

LINE CHART DO’S AND DON’TS

Do:

• Use a scale that clearly shows changes over time

• Use even increments of time

Don’t:

• Use too many lines

WHEN A LINE CHART SHOULD BE SOMETHING ELSE

When you have… Instead of a line chart, you should use…

Uneven increments of time Bar chart

Too many lines Bar chart or table

Not enough variation in data over time

Table or text

PIE CHART DO’S AND DON’TSDo:

• Use pie charts to show parts of a whole

• Make multiple pie charts proportional in size

Don’t:

• Use fewer than three or more than about six slices

• Use more than one pie to compare apples and oranges

• Use slices that represent 0%

WHEN A PIE CHART SHOULD BE SOMETHING ELSE

When you have… Instead of a pie chart, you should use…

Too many slices Bar chart or table

Too thin slices Bar chart or table

Only two slices Text

Changes over time Line chart

PICTOGRAPH DO’S AND DON’TS

Do:

• Get creative when the audience and subject matter warrant

• Use proportionate size to indicate data

Don’t:

• Use a pictograph just because it looks cool

• Use three-dimensional objects to represent anything except volume

WHEN A PICTOGRAPH SHOULD BE SOMETHING ELSE

When you have… Instead of a pictograph, you should use…

Very technical or serious audience or subject matter

Chart, table, or text

Wide variation in size of data Chart, table, or text

Data that must be shown precisely

Chart, table, or text

Geographically sensitive data Something other than a map

FURTHER RESOURCES

“Save the Pies for Dessert,” by Stephen Few [e-newsletter article, www.perceptualedge.com]

How to Lie With Statistics, by Darrell Huff [book]

The Visual Display of Quantitative Information, by Edward R. Tufte [book]

Making Data Meaningful, United Nations Economic Commission for Europe [e-book series online]

Statistics Canada’s Learning Resources: Power from Data! www.statcan.gc.ca

http://flowingdata.com

http://ilovecharts.tumblr.com