A Checklist For Good Graphical Practice

A Checklist For Good Graphical Practice

From: Gordon & Finch (2015) “Statistician Heal Thyself: Have We Lost the Plot?”, JCGS, 1210-1229,

These questions and suggestions are a useful set to apply to graphs designed for presentation purposes. I don’t agree with all of them, but they are a very good start for things to think about in graphical practice.

How clear is your purpose in communication?

• What relationships or patterns can you identify in the graph?
• Are these the relationships or patterns you intended to represent?
• Can the viewer identify the patterns you wish to illustrate?
• Are the important comparisons you wish to show salient?

Make clarity a high priority.

• Does the graph have a clear title?
• Are the axes labeled?
• Are the units of the variables measured defined?
• Are the units of observation clear?
• Is the graph large enough?
• Would ordering groups or variables plotted improve the graph?
• Are all the graph labels horizontal?
• Use points to plot estimates (e.g., means, proportions) rather than bars.

Choose standard forms fit for your purpose.

• Use bars around points to indicate the precision of the estimates.
• Plot the estimates of interest (e.g., mean differences with confidence intervals) rather than standard summary statistics (group means).
• Plot inferences to support stories about models.
• Plot data to support stories about distributions and variation.

Consider detection issues.

• Can all the data points be seen?
• Are patterns in the data clear?
• Are the fonts large enough?
• Would it help to use jittering, or another form of representing multiple, identical values?

Would panels help?

• Are there grouping variables that can be used to panel the graph?
• Do the grouping variables correspond to the variation of interest?
• Would additional panels help?

Align quantities to be compared on a common scale.

• Has distortion of the data been avoided by using the same scales for the same measurement?
• Are measurements made on the same scale plotted on the same scale?
• Would transposition improve the graph?

Does the graph have grid lines?

• Light gray grid lines will help with accurate interpretation.

Are all the elements of the graph defined?

• What do points on the graph correspond to?
• Are estimates (e.g., means, proportions) plotted on the graph clearly defined?
• Are bars around points on the graph clearly defined?

How much decoding work does the viewer have to do?

• Is it easy for someone unfamiliar with your data to interpret your graph?
• Does the graph stand alone?
• Try it on a friend!