Comments on: Bad Graphics – Stacked Pyramid Chart

By: Jon Peltier

Jon Peltier — Fri, 24 Feb 2012 18:13:32 +0000

Neil -

Yeah, it’s possible, but it’s not straightforward, and I don’t want to encourage sharts that I don’t think are effective.

By: Neil

Neil — Fri, 24 Feb 2012 15:01:23 +0000

I agree with all of your comments, I want it to be accurate as well as nice looking. However, in the case of the dashboard I am developing, a pyramid is the recognised way of representing the data theoretically, see below link:

http://www.osg.com/siteFiles/Newsletter/1F26C0C2A9F88A9E06399E15F775FAFC.jpg

This shows H.W. Heinrich’s Safety Pyramid which proposes that minimizing near misses reduces occurrence of major injuries. Therefore I would really like to show this triangle with real data for all of our offices using a stacked pyramid chart that is not misleading. Ideally I don’t want it 3d, just a flat view like yours above but which represents the data as areas not heights and turns it into a stacked pyramid. Is this even possible in Excel?

I would be grateful for any help with creating this. Alternatively I will just produce it as a stacked bar but this isn’t as asthetically pleasing than displaying it as a pyramid.

Cheers
Neil

By: mermaldad

mermaldad — Tue, 08 Dec 2009 16:34:26 +0000

To me, the purpose of a stacked pyramid is to express a relationship between the layers. The lowest layer is the foundation upon which higher layers depend. As you noted, the eye naturally sees the volume of each layer as indicating the magnitude of whatever is being measured. A reasonably good example of this is the USDA food pyramid, where the volume (or area) of the layer indicates how many servings of each group one should eat. Moreover, if the because the eye is only so-so at comparing the volumes of the layers, the pyramid is best used when the numbers aren’t the main point.

The chart above ignores all of this. It’s not that the stacked pyramid is bad, just that it is easily mis-used.

By: Jon Peltier

Jon Peltier — Sat, 26 Apr 2008 14:32:55 +0000

I suspect they use thickness because (a) the algorithms are easier to implement, and (b) they haven’t even thought of using a different apparent ‘size’ property of the sections. probably a good thing, because these can be improved on only by using a uniform section, viewing the section as a 2D shape, and unstacking the sections.

By: Damir

Damir — Sat, 26 Apr 2008 12:58:03 +0000

One could simply rotate the bar-chat around the category axis to get truncated-conical shape which can then be used as a funnel or pyramid chart. In this case the width of a disc-element would be proportional to the category value. Why do they do thickness is beyond me.

By: Jon Peltier

Jon Peltier — Tue, 22 Apr 2008 21:52:47 +0000

Oh, that’s nasty. I guess it plots by thickness, too, like the pyramid.

I’ve seen funnel charts which were supposed to indicate a process of filtering out items, so each stage of the funnel is supposed to contain fewer items. This would be good, for example, for tracking the success of development projects, where you might start with 100 projects, 90 pass through the initial feasibility stage, 75 pass preliminary design, 50 go on to detail design, 25 pass technical review, and 10 are released to manufacturing.

However, I think that a column or bar chart best illustrates a filtering process at work. The funnel analogy is lacking, because it seems to me that everything squeezes through the entire ever-diminishing cross section of a funnel. Pressure and friction increase, and nothing is really filtered out. And if you get an artistic graphic designer drawing the funnel from a 3D perspective, I don’t know what it looks like.