Communication of crime statistics

Sir David Norgrove, Chair, UK Statistics Authority writes to Sadiq Khan, Mayor of London.

Dear Mayor,

My attention has recently been drawn to various statements issued by you and by your office regarding trends in crime. I was asked specifically about your use of police-recorded crime statistics to describe trends in crime and violent crime.

This is a complicated area, with two main sources of data.

The Crime Survey for England and Wales (CSEW) is the most reliable indicator for long-term trends in crime overall. Unlike police-recorded crime, the CSEW is unaffected by changes to police recording practices.

The CSEW shows that crime generally has fallen in England and Wales in recent years, though the trend seems now to be levelling off. It is not the case that crime has been rising nationally, as has been suggested in some of your recent statements.

While police recorded crime has significant limitations, it is better suited than CSEW to measuring trends in some of the more harmful crimes that occur in relatively low volumes (such as knife crime). The most recent crime statistics find that police-recorded crime shows a likely real increase in some higher-harm, violent offences.For example, police recorded 16 per cent more offences involving knives or sharp instruments this year, compared with last year. This is supported by NHS data.

The one exception to your generally accurate statements in relation to this category of crime was in a tweet of 17 July, which had wrongly referred to violent crime doubling in Hampshire, Essex, Cambridgeshire, Warwickshire and Norfolk. I am pleased your office has said they will remove this tweet.

I welcomed the Greater London Authority’s announcement, last month, that it was choosing to comply voluntarily with the Authority’s Code of Practice for Statistics. Under the Code, it is important that public communications describe statistical trends accurately, with appropriate balance and caveats. The Authority would be happy to assist your team, in interpreting and communicating statistical information in the complicated area of crime.

I am copying this letter to Mr Oliver Cooper, Leader of the Opposition, London Borough of Camden.

Yours sincerely,

Sir David Norgrove