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Data Graphics

A Collection of Poor Data Graphics

This BBC article on the budget contains no less than six data graphics – and there’s something wrong with every single one.

By “something wrong”, I mean either:

  • I have to concentrate on the graphic, rather than just glance at it, to understand what it is trying to show, or
  • The numbers are distorted by the graphic – the worse kind of “wrong” as a glance at it could mislead.

The issues are:

  1. UK Budget Deficits: Apart from the unwieldy x-axis labels, showing every second fiscal year, my main gripe is the projected section of this stacked bar chart. It only works because the three projections don’t “swap over” their values at any point. But I still had to look at it for longer than necessary, to realise that the “upper value” stacked bars run “behind” the lower ones.
  2. Long-Term UK Government Debt: The use of a line chart, with smoothly flowing lines, rather than bars suggests that there are values available on a more frequent basis than every year – or that the joins between each yearly point are just artistic and so misleading. If the former, then having the unwieldy “fiscal year” x-axis, with ticks every five years, is unnecessary – why not just shift the tick marks back by 4 months and have normal years? This would be considerably easier to read. If the latter, then that’s just plain misleading!
  3. Treasury Growth Forecasts: The worst one of all. The addition of direction arrows above the positive bars (or below the negative bars) – with the value between them and the bar, and the arrows coloured the same, made me assume the bar ran up to the top of the arrow – massively increasing the value of the 2010 independent forecast, for instance. Not sure why the colours needed to change from the first chart, either, seeing as at least two of the categories have the same source in both charts.
  4. UK Claimant Count: This is a simple sequence of choropleths and as such really shouldn’t be a Flash-based chart – this is trivial to do in HTML/CSS alone, never mind Javascript. The colour sequence is odd too – a series of blues suggesting a value-based ordering, which then arbitrarily switches to purple for the final one/two bins. (The legend changing slightly for the last two!) The choropleth is also too small, so show the needed detail.
  5. Government Spending/Taxes: 3D pie-charts, tut tut! The tilt exaggerates the values at the front, making them seem bigger than they are.
  6. UK Rescue Plans: The circles are correctly scaled in 2D rather than 1D – a common mistake averted. However, they unnecessarily overlap with each other, so partly obscuring the genuine ratios

The Beeb designers need to take a read of Tufte and not go down the Microsoft Excel route!

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