Knife crime

I woke up today to hear a very hyped story about murders involving knifes. The Conservatives, needing to make Labour look soft on law and order, told us that ‘Knife killings have soared to a record high in England and Wales… citing police figures obtained under freedom of information laws.’ (Reuters)

As with all reporting of government statistics, there is some confusion as to what they mean. Reuters reported that there were 277 killings between April 2007 and March 2008, whereas the Times said this figure was ‘so far this year’. Reuters also got it right when it reminded us that the figures include all ‘sharp instrument deaths’ (including bottles and glasses, spears(?) and so on, whereas the papers assumed they were all stabbings with a knife.

There is no argument that this number is a record high (since records began in 1977). However, for this to represent evidence for a breakdown in society (‘underlying causes of crime such as drugs, family breakdown and gang culture’ Conservative home affairs spokesman James Brokenshire) it’s important to make sure that the change is significant. After all, the Times also reported that:

In spite of the increases, as a proportion of all homicides, deaths caused by a knife or other sharp instrument have remained broadly stable for the past 30 years.

Does this mean that knife murders and all murders have rocketed?

Not really.

Chart of homicides in England and Wales, 1964-2008

Homicides have been increasing steadily, but have been fewer in the past few years. It looks like they’ve trebled since the 60s, but once population increases are stripped out they’ve only doubled. However, there’s still an increase over all.

Although we can’t see the full figures yet, my bet is that the homicide rate has fallen, but knife killings have increased. Because all these movements are quite small (e.g. 277 this year versus 259 last year, I think), the proportion is ‘broadly stable’. Indeed, because killings are such a rarity in the UK, a small change  of 18 more is a big percentage increase, but easily within an expected range.

Furthermore, the changes in methods may indicate better policing (and so could be a good news story). If ‘sharp instrument’ killings are going up as killings go down, does this mean that shootings have fallen? Is the increase in knife crime due to guns being taken off the streets?

Finally, it’s worth pointing out that the England and Wales homicide rate is really very low at 1.37 murders per 100,000 population. This could be compared to:

Scotland 2.56
Europe 5.4
USA 5.7

As always, it needs to be said that any killing is a tragedy for those involved. But there’s no ‘soaring’, no problem growing dangerously out of control. The story of knife crime is hyped by the two main political parties (to appear tough) and by the media (to beat the politicians).

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Filed under News, Politicians, Statistics and simplicity

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