In last week’s post, I described how, while teaching data visualization to thousands of professionals, I was surprised to discover that many audiences don’t know how to read chart types that many chart creators assume are widely understood, such as scatter plots and histograms.
In this post, I’ll list the specific chart types that, in my experience, stump audiences most often (including, sometimes, senior executives).
I want to be clear that I’m not saying that these chart types should be easier or harder for audiences to understand. I’m saying that these chart types are the ones that I see audiences getting stumped by most often out there in the real world, regardless of whether you, I, or anyone else thinks that should or shouldn’t be the case.
In my experience, common chart types and techniques tend to fall into the following four groups, listed from the lowest risk of stumping an audience to the highest:
🟢 Safe for most audiences: Simple bar charts, line charts, pie charts, maps, heatmaps and shape size (proportional symbol) charts
🟡 Low risk: Stacked bar charts (yup, I’ve seen people misread the top of the stack as the value for the top-most segment instead of the whole stack), stacked area charts, clustered bar charts, treemaps, arrow charts, inset charts
🟠 Moderate risk: Bumps charts, step charts, needle charts, strip plots, bullet graphs, simple small multiples
🔴 High risk: Scatter plots and bubble charts, connected scatterplots, histograms, Pareto charts, box plots, 100% stacked bar charts, 100% stacked area charts, dot plots (especially when showing time series data), waterfall charts, frequency polygons, index charts
I know that the risk of using each of these chart types varies from one organization to the next, and that there are plenty of data-savvy organizations in which all of these chart types are “safe.” My point is that there are also plenty of organizations in which people don’t know how to read the “riskier” chart types.
Also, I’m not saying the higher-risk chart types should be avoided (except possibly for box plots and connected scatterplots). I’m saying that it isn’t safe to assume that most audiences know how to read them, or that they can be grasped in a few seconds. If you need to use one of the riskier chart types—and, sometimes, you have no choice—don’t be surprised if you get confused looks and must spend several minutes (or more) teaching the audience how to read them, assuming they’re willing to give you the time and attention to do so.
BTW…
Registration is now open for my upcoming live online public workshop in February! Interested in taking my Practical Charts and/or Practical Dashboards course? Early-bird discount ends Jan. 15. Info/registration page: https://www.practicalreporting.com/feb-2025-workshop