Bullet graphs encode a single variable as a bar. It looks a lot like a bar graph, with just one bar represented. However, a bullet chart adds some extra context that makes it powerful. Most bullet graphs also show a target line and, in the background, some shaded performance levels. Typically bullet charts are included in dashboards because they pack a lot of information into a tiny amount of space.
CIO Dashboard featuring two sets of bullet graphs
This dashboard contains many graphs and lots of data but notice the bullet charts in the middle and on the right.
Source: Veronica Smith. Retrieved from http://www.ndedataviz.com/chapter-6--data-dashboard-as-evaluation-and-re...
Advice for CHOOSING this option (tips and traps)
If you have a target or benchmark, a bullet chart is a good idea. You do not necessarily have to include levels of performance in the background, even though this is the technical definition of a bullet graph. Bullet graphs can also be used outside of dashboards, in more traditional data displays.
Advice for USING this option (tips and traps)
Performance areas should be in the background and muted in colour because they are supporting but not primary information. Target lines are often red but can be any colour that will sufficiently pop out to the viewer.
Step by Step guide to making Bullet Charts in Excel: Jon Schwabish’s slideshare details how to make bullet graphs in Excel.
Stephanie Evergreen’s blog shows some alternatives if you don’t need areas of performance in the background. This one plots a bar graph in line with a row of data in Excel: Easy bullet charts in Excel. This one adds a target line to a bar graph: Adding a Benchmark Line to a Graph.
Bullet Graph Design Specifications: Stephen Few, the inventor of the bullet graph, outlines the design specifications and includes performance areas.
Other ways to compare sets of values
Illustrating the main features of the distribution of a data set in a clear way.
Presenting a frequency distribution of quantitative data in a graphical way.
Providing a way to communicate complicated data sets quickly and easily.
Deviation bar graph
Aligning two bar graphs along their spine to compare the shape of their data sets.
Plotting two or more dots on a single line for each category being compared.
Positioning several small graphs with the same scale in a row for easy comparison.
Few, S. (2013) Bullet Graph Design Specification. Perceptual Edge. Retrieved from http://www.perceptualedge.com/articles/misc/Bullet_Graph_Design_Spec.pdf