Remember those bags o’cash?

Here’s some more, in an infographic showing the increase in personal tax allowance over several years. And me holding up the relevant page in a book called “How to lie with statistics” all about how showing a change in the size of a figure using a picture may mislead. As I work in a politically restricted post, I emphasise the word “may”

Below is text from the relevant page that I’ve blown up nicely for you.

The point being, if some number doubles, and this is shown as a bag of cash which is twice the size, then that actually means it’s increased it’s area by 4 times, so it looks much more than it really is.

So I printed off the offending bags o’cash picture and measured the dimensions with a wooden ruler, put the numbers into excel and let maths sort it out. Being as mathz roolz.

The increase between the size of the smallest bag and the biggest is 1.31 times. But the actual numbers on the bags, the increase frim £200 to £593, the thing being measured, is 2.96!

So I apologise. The graphic seriously undersells the actual increase, showing it in bag form as only half the increase what it is in actual cash.

Perhaps whoever did this was keenly aware of geeks with wooden rulers just waiting for an unthinking designer to slip up, and so erred on the side of safety. But the point remains, a photo of a bag o’cash getting bigger has little to do with the actual increase. It’s a nice addition to help sell the essence more effectively, but is more graphic than info.

Perhaps they should have employed a small child to do this chart.