Low numbers + small change = BIG NEWS

 by Martin Belam, 19 January 2012

There is a great piece on the Guardian’s Data Blog today by James Ball about the statistics behind the apparent extravagance of the Met running up a bill of £35,000 on the speaking clock, but it is another set of police related data stories that have grabbed my attention today. Yes, the annual round of writing up crime statistics.

The Guardian went for “Murder rate rose 5% last year”, the Mail with “Knife-point robberies leap by 10% in just a year” and the BBC also lead with that figure. On a more local level, Wales Online went for the happier news that “Crime in Wales drops 7% in a year” and Kent Online reported “Crime falls in Kent”.

I went to a fascinating event last year about the reporting of crime statistics, which was eye-opening about the way crime is recorded and the ways in which the numbers can be unhelpfully reported.

Take the 5% rise in the murder rate for example, that 5% represents a shift from 608 to 636, and twelve of those were one shooting rampage. Effectively in England and Wales we saw a shift from 1.66 people being murdered a day, to 1.77 people. Not a massive change. And you’ll note that the three national news sources there all went with headlines that pull out an individual type of crime that has increased, whilst the Press Association opened reports with the line “The number of crimes recorded by police in England and Wales fell by 4%.”

At the event, which was put together by the Media Standards Trust, the BBC College of Journalism and the Royal Statistical Society, Andrew Trotter, the Chief Constable of the British Transport Police, described accurate reporting of crime statistics as “a hopeless quest.”

In my blog post about his talk I wrote:

“Politicians, journalists, and sometimes the police themselves abuse crime figures he said. Politicians use any movement in the numbers to prove that their policy works, or someone else’s doesn’t...And police officers are guilty of that too, Trotter said, for example claiming that some specific operation drove numbers down, without accounting for longer term factors. He recognised that there is no scientific rigour in isolating the factors that might be causing changes in crime figures.”

Also talking that day was Michael Blastland, who has spoken at London IA about “Designing for doubt”. At the statistics event he said that “society was ‘twitchy’ about crime figures, always looking for trends, and the media made stories out of what they saw to be trends, even if the movements in the figures were well within the margins of error or ‘confidence levels’ in any given set of statistics.”

If you are interested in the way that the media report crime data, then I’d recommend reading the blog posts from that day in full:

Keep up to date on my new blog