THE CHART CLINIC CHARTS NEED HELP. WONT YOU HELP THE CHARTS? LAUREL HYATT, 9 JUNE 2013 © Laurel Hyatt

BAR CHART DOS AND DONTS Do: Make the Y axis 0 if possible Show scales (such as years) in even increments Dont: 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 dataText Too much or very precise dataTable Even-year time seriesLine chart Parts of a whole (percentages add to 100%) Pie chart

LINE CHART DOS AND DONTS Do: Use a scale that clearly shows changes over time Use even increments of time Dont: 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 timeBar chart Too many linesBar chart or table Not enough variation in data over time Table or text

PIE CHART DOS AND DONTS Do: Use pie charts to show parts of a whole Make multiple pie charts proportional in size Dont: 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 slicesBar chart or table Too thin slicesBar chart or table Only two slicesText Changes over timeLine chart

PICTOGRAPH DOS AND DONTS Do: Get creative when the audience and subject matter warrant Use proportionate size to indicate data Dont: 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 dataChart, table, or text Data that must be shown precisely Chart, table, or text Geographically sensitive dataSomething other than a map

FURTHER RESOURCES Save the Pies for Dessert, by Stephen Few [e-newsletter article, 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 Canadas Learning Resources: Power from Data!