Wednesday, 2 November 2011

How to call bullshit on statistics. e.g 2

This article has got a lot of press coverage as well. It contains a startling claim:

Goodall says, "our total use of materials [in 2007] was almost the same as it was in 1989, despite the economy having tripled in size in the intervening years

This falls into the A Second's Thought Should Tell You It's Wrong category.

A tripling of the economy in the years from 1989 to 2007 would require a growth rate on average of 3^(1/18)-1 which equals 6.4% per year, every year. I'm not going to look up the data, but I'm pretty confident the UK hasn't grown that fast in a year in the past 30 (and hardly ever - perhaps the Barber boom peak?). In fact between those years UK GDP rose by 59%, a rate of 2.6%.

So what does he mean? I know where the figure comes from - it is true that UK nominal GDP rose by 3 times between 1989 and 2007. Clearly this was mostly inflation, ie a rise in prices. There's no reason why a rise in prices should require more 'stuff', and of course to use such a figure is completely wrong.

To be fair to the academic, it might be a journalistic or sub-editing error as the original paper doesn't contain the statistic.

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