I’ve recently seen a few comments on LinkedIn from people who don’t feel that it ever makes sense to use a stacked bar chart to show the breakdown of a single total, like this:
It’s true that, if the main message of the chart involves precisely comparing the parts of a total with one another, a regular bar chart would be a better choice:
It’s also true that, if the main message of the chart involves showing what fraction of the total each part represents, a pie chart would be a better choice:
(BTW, if you believe that pie charts are the devil’s chart type, read this.)
If other chart types are better choices in those situations, when would it possibly make sense to choose a stacked bar chart? TBH, it took me a while to realize that there’s another type of insight that one might need to communicate about the breakdown of a total, and for which a stacked bar chart would be the truly best choice, specifically, an insight that involves showing subtotal(s) of the values of several parts:
If you were to use a regular bar chart or pie chart to communicate this type of insight, it would force the reader to do math in their head, which is definitely something to avoid since it dramatically slows down interpretation and increases the effort required from the reader:
Note, however, that if the main message of your chart involves showing what fraction of the total several parts represent, a pie chart becomes a better choice than a stacked bar chart:
So, to sum up, when showing the breakdown of a single total…
Consider using a stacked bar chart when showing subtotal(s) of parts is more important than…
…allowing the parts to be compared with one another precisely, or…
…allowing fractions of the total to be perceived precisely.
So, yes, there is a situation in which it makes sense to use a stacked bar chart; it’s just that that situation doesn’t occur all that often in practice.
These guidelines (and others) are summarized in this handy-dandy decision tree, which is one of eight such tools that are included in my Practical Charts course:
Having said all this, if you need to show the breakdowns of several totals (not just one total, as we’ve seen so far), stacked bars become the best choice considerably more often:
When, exactly, are multiple stacked bars the best choice? That would require a whole other article, or you could just take the course😊, speaking of which…
If you’re interested in attending my Practical Charts or Practical Dashboards course, here’s a list of my upcoming open-registration workshops.
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