A bonus lesson in my data-handling tutorial

I’m a fan of in-lecture voting to student enhance engagement. We currently use the Keepad Turning Point system. On the whole it works well, however I’ve noticed previously that the visual display of data is sometimes sub-optimal. During my session this afternoon – appropriately enough on the theme of data presentation – the system handed me a bonus illustration.

How *not* to display a 2% difference

How *not* to display a 2% difference

The question asked the first year students to consider whether or not it was appropriate for a specific graph to be extrapolated back to the origin (I won’t say which answer I favour here, there’s another two groups to do the session next week!) The vote on this is always reasonably close, but this time (n=approx 85, depending if any failed to vote in time) the call was as close as it could get without being a tie – 51% voting against, 49% in favour. Given this tight margin, the automatically-generated graphic is absurd. Still, it did allow to point out that similar skewed representations in their work would score badly.