How to create a bullet bar chart
The bullet bar or bullet graph is one of the very few "new" chart types which were not invented already a long time ago. It's creator is data visualization expert and book author Stephen Few, who devised the concept in 2005.
The intention of the bullet bar is to enhance the informative value of graphics, specifically the bar chart. This is achieved by a specific layout and additional indicators. Though the bullet bar provides more information it needs less space. This, in combination, makes the bullet bar so usable. The bullet bar is easy to read and provides a quick visual comparison, even for people who do not even know what kind of chart this is.
As an illustrative and widely usable example: If you have a story of the (numerous) examples where targets have been missed, this is the chart to use. Think of large public building projects and how they failed to be on time and on budget.
1. Preparing and importing the data for a bullet bar
When looking at the bullet chart above, you can see what kind of information your dataset has to contain. You will need a table formatted as follows. You need three columns, one for the category and two for the values to compare.
|Project||Planned costs||Actual costs|
|Elbphilharmonie - This building saw costs rising 15-fold, from 70 to 600 Million Euro.||0.07||0.6|
|Electronic Health Insurance Card - Originally costs for the introduction where planned for 1,6 Billion Euro, experts estimate the current budget at at least 5 Billion Euro.||1.6||5|
|Flughafen Berlin - A series of problems lead to a rise from 2 to 4,3 Billion Euro.||2||4.3|
|Stuttgart 21 - Costs for Stuttgarts new railway station rose from 2 to 6,8 billion Euro.||2||6.8|
Source: Spiegel Online
Here is how to prepare your data for a bullet bar:
- One header row containing labels
- The first columns contains major categories that will be displayed as descriptions on the left side of the chart
- The following columns are categorical dimensions: The second column will contain the "inner bar" and the third column the "outer bar"
- Comparable measures for categorical dimensions
- Each row corresponds to one row in the chart
In this case, we have five different labels, i.e. different projects. The bullet chart will work just fine with one or more labels. Optionally, you can refine your labels by using html code to give additional information. Be aware that the cells of your table must contain values of the same measure/currency as they define the sizes of the bullet bars. Once your dataset looks like this, you can upload or copy & paste it to Datawrapper.
2. Check & Describe
Below is a screenshot on how your table will look in Datawrapper after you uploaded it. Make sure that the box "First row as lable" is ticked so that Datawrapper correctly assigns the values to the labels.
Click on "Proceed" and Datawrapper will take you to the next step.
Once you're in the "Visualize" tab, choose "Bullet bars" and Datawrapper will create a first iteration of your data. Continue with the steps refine, annotate, and design to finish your chart. We cover this in a separate short tutorial found here.