No self-respecting law and order speech can be seen in public these days without being heavily punctuated with bullet points and ornamental digits from the latest crime figures. Yet rhetoric bejewelled with statistics brings no real policy changes. This is quite ironic, as statistics were originated precisely to permit governments to make sound social policy in accordance with hard evidence.
The formal use of statistics originated in the 17th century as (etymologically) "a science dealing with facts of the state". It was the writer William Petty who really began the process of gathering and using numerical data which he thought might help in making policy decisions and in judging the "moral health" of the nation. In his work, Political Arithmetic, in 1699, he became the first person to advocate collecting crime figures as a better way of guiding policy than the futile strategy of "using only comparative and superlative words".
He wanted to make intellectual arguments about policy superfluous by "finding the facts".
Finding what all can agree upon as "the facts", however, is not as simple as someone like Dickens's Mr Gradgrind ("facts alone are wanted in life") would have liked.
Much crime is unreported to the police and so never ends up in the statistics. The Home Office's periodic British Crime Survey estimates that the true level of crime is more than three times higher than that registered in the annual statistics. Businesses often do not report crimes for fear of lowering their public image, and many citizens today are not insured against car theft or property loss (because they cannot afford the premiums) so they have no incentive to tell the police if they become victims.
Sometimes a sharp rise in crime can come from a new policing policy - for example, offences of "lewd dancing" rose by about 300 per cent during 12 months in the Eighties in Manchester, but only because the zealous Chief Constable, James Anderton, had deployed a great many officers in gay night-clubs.
Sometimes the enactment of a new range of offences, or the possibility of committing old offences in a new way (such as computer offences involving fraud and deception) can cause an upward jolt in crime levels. Conversely, if crimes such as joyriding and some assaults are kept out of the categories measured in the annual statistics, as is the case, the official figures do not reflect even what is reported to the police as criminal.
The way that criminal statistics are compiled by the Home Office is also relevant.
From April this year, police forces started to count crime in a way which, according to the Government, will give "a more robust statistical measure". Under the new rules, crime will be recorded as one crime per victim.
Some crimes, such as assaults, have always been recorded in this way, so the main impact of the change will be in the area of property offences. The old rules for shop thefts, for example, counted the offenders, but will now count the victims. Multiple thefts from cars in a car park with a barrier were previously counted as one offence, but are now counted as separate offences.
Yet, despite all the uncertainties with some aspects of the figures, many statistics present such a clear, strong steer that we ignore them at our peril.
If tests show that in the event of a car accident you are 80 per cent more likely to survive if you wear a seat belt, the lesson is obvious.
The political will of some governments, however, has seemed to be perversely at loggerheads with "the facts".
Consider the use of prison. It is manifestly not an effective cure for crime. Eight out of ten people sent to prison have been convicted of a non-violent crime, and rates of recidivism are high: five out of ten people discharged from custody in 1992 had been reconvicted after two years. It costs about pounds 35,000 to keep a prisoner in prison for a year.
Yet prison building continues apace, and one Home Office figure estimates that by 2005 we shall have more than 90,000 people in jail - a doubling of the prison population in just 20 years.
Last year it was the 160th birthday of the annual British crime statistics - for this body of knowledge, the more mature it gets, the more vital its statistics become. Let us hope that it soon begins to turn a few more heads in its direction.
Dr Gary Slapper is the director of the law programme at the Open UniversityReuse content