Dot Plots

Today I was reading Stephen Few’s Information Dashboard Design aloud while Josh was doing some fall PC clean up and was on the chapter “An Ideal Library of Graphs.” As Stephen describes it there are several charts or graphs that should make their way onto dashboards and he goes into detail on the reason behind each and how to properly apply them.

We stopped to discuss the dot plot, because it is one that both of us under utilize.  From my perspective there’s a lot of under utilized space below each dot.  As we were exploring it deeper, I also felt uncomfortable with dots above a certain threshold, because at that point the actual data point was lost.  We decided to open up Tableau and start playing around.  In my mind I was thinking that using a Gantt bar as the point would better represent the data.  (Mind you, Stephen says that you use dot plots when you may not go to zero, otherwise stick to bar graphs).  I thought Gantt bars presented the perfect “happy medium” between the dot plot and the bar chart without causing the end data reader to incorrectly visualize length.

Below are the four different representations we came up.  All things equal, I think I might be most partial to the ‘Plus Plot.’  I think the general shape tends to draw your eye directly to the center point, and even if they were larger you’d still know where the center was.  I can see how this might get cluttered quickly, or if more encoding were done things could go awry.

I also found that I liked the Gantt bar, but needed to shorten the bar significantly to eliminate mentally drawing drop lines and visualizing as bars.

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