The Treasury’s log rolling
The Treasury has been slapped on the wrist by the UK Statistics Authority for messing around with the scale of charts.
Here’s what the Treasury produced in its National Infrastructure Plan document:
This is designed to show a lot of projects in the pipeline. But look carefully at the scale: each interval is 10 times larger than the previous one (this is known as a logarithmic scale). There are times when log scales in graphs are useful, but this is not one of them. This chart serves to flatter the impression of the contribution from some sectors.
Not such an impressive picture of projects in the pipeline.
But here’s a mischievous thought: what if the Treasury’s dodgy graphical practices were applied to some key public finance charts?
Here’s the national debt in cash terms:
But let’s produce it with the Treasury’s log scale:
Voila! The debt pile looks pretty stable. So why all the panic about Britain being on the verge of bankruptcy in 2010?
How about the deficit?
Here’s public sector borrowing in cash terms:
George Osborne says it shot up under “spendthrift” Labour and the Coalition boasts that they have reduced it by a third.
But let’s use the magic log scale:
Hey presto! It was always quite high and its hasn’t come down since.
So what happened to all that impressive deficit reduction that ministers tell us about?
The lesson is that messing around with logs is hazardous – they can roll back on top of you.Tagged in: log scale, UK Statistics Authority
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