Saturday, February 28, 2015

Neither Smart nor Balanced

I'm on a crusade against bad data viz in education. For an industry so consumed with being "data-driven," we don't display it very respectfully. Vendors out there don't help. Instead of hiring data designers to develop visualizations that support educators in getting the most information from their data, we instead get things like this:


Can we talk about this chart from Smarter Balanced?

Here's a brief list of things that make this chart difficult to use:
  • The title is centered. In the western world, we start reading at the top left. When you change that for a chart (or slide or document) then the audience has to use time and cognitive processing to figure out how things are organized...leaving less "head space" to interpret the information.
  • The y-axis label needs to be turned 90 degrees so we can read it easily.
  • There is way too much ink here in relationship to the data. We don't need tickmarks on the outside of the chart. The "%" signs in the stacked bars are redundant---we've already said they're percentages in the title. Axis titles don't need to be bold. We also don't need the y-axis scaled by 10.
  • The colors are awful. Not only do we have the ubiquitous red-yellow-green, which is not very accessible for all vision types, the shades selected here are particularly gaudy. Are we clowns? Do we amuse you?
  • Finally, humans do best at judging length and position (out of all the pre-attentive attributes). This chart takes advantage of neither.

So, let's fix those things.

 Okay, we're getting there...but we still have a problem. It's very difficult to make any comparisons among the groups represented. This is an issue common to stacked bars---in either vertical or horizontal forms.

What if we line up the bars at the division between not meeting and meeting standard?

When we "float" the bars on the chart, we not only have all the information we need, we can more easily dig a little deeper for comparisons between grade levels. (If you like this sort of chart, there's a tutorial on Ann K. Emery's blog.) I could probably improve this one a bit by playing with the x-axis, this one is still a vast improvement over the original...if I do say so myself.

Here is a before and after comparison---same data, different presentations:

So, Smarter Balanced, what do you say? Can you start making an effort for us and get some meaningful data visualizations to go with the new system?

You can also download my workbook for this chart.