The 3D Challenge - can you read this chart?

It seems that attendance keeps cropping up as an area that schools struggle to deal with graphically. Take this example (taken from a university course):
Firstly, we must keep reminding ourselves who the audience is for these visualisation - professionals or parents / students. Almost exclusively the audience will be parents / students who come to the visualisation with a different set of skills than the professionals who prepared it.
Without de-constructing this chart - can you make immediate sense of it? OR do you need to work at understanding what it's showing?

The challenge with this visualisation is that it shows two different things on one chart. It shows:
  • Grades broken down by attendance AND
  • Attendance levels broken down by grade
From the chart you can see:

  • At greater than 90% attendance, the most common grade is A
  • For 60-90% attendance, the most common grade is B/C
  • For less than 60% attendance, the most common grade is C/D

  • Those learners achieving an F, most of them had attendance less than 60%
  • Those learners achieving a B, most of them had attendance of 60-90%
  • Those learners achieving an A, most of them had attendance of greater than 90%

The challenges to reflect upon though are - "how much effort was needed to extract this information?" and "should we expect an average, normal parent to work at understanding our data?"

Some Excel-fu later:

We can average the data to show the mean average grade per attendance level. It's easy to see that the higher the attendance, the higher the average grade. BUT we have lost any information about the higher grades (it looks like our learners never get an A grade).

If we are interested in preserving the visualisation of the higher grades then we could consider a panel chart, with each panel representing an attendance level (this is almost the same as the original 3D chart, opened out and laid flat)

Call to action
  • Never use 3D visualisations (unless you're a mathematician visualising an xyz function)
  • Keep it simple
  • Know your audience
  • Less (as always) is more

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