Figure it out

Years ago, when the Times was a newspaper for grown-ups, it was said to have published a letter illustrative of our misuse of statistics. This was to the effect that there were about 3 million people in Wales, of whom about 3,000 had one leg and 300 no legs at all. Thus, the ‘average’ number of legs per person in Wales was 1.99 whatever, and therefore ‘most’ people in Wales had fewer than two legs.

We read such basic statistical errors daily. Even the sad figures for road deaths over the Christmas period — intended to shock — are sometimes misleading, albeit differently, because it’s not always pointed out that Christmas figures are usually significantly lower than those for other times of the year. Or — different again — when the London Health Observatory tells us that road accidents in London ‘cost’ the health service £29 million, can we be sure that this figure does not include salaries and capital costs that would have been paid anyway? Did they set the cost of the unfortunates who died against what they would have cost the health service if they’d lived to die of natural causes?

Happily, there are many more cheerful transport statistics to be found on the Department for Transport website at www.dft.gov.uk. It is a pleasure, in these environmentally obsessed days, to find that there were nearly twice as many cars of over three litres on the road in 2003 as there were in 1993. Nor are they all 4x4s (some of which, incidentally, score better in pedestrian crash tests than conventional saloons). Unexpectedly, the north-east tends to have the newest vehicles (average age 5.7 years) and London and the south-west the oldest (6.9). Twenty-nine per cent of vehicles tested failed the MOT test last year, compared with 38 per cent ten years before, with faulty lights the most common cause.