Labour's Tony Blair says that crime is down 30% since 1997. Conservative leader Michael Howard says that crime is up 15% since 1998. So who is right?
There are two measures of crime in England and Wales.
One is based on the crimes reported to, and recorded by, the police.
The other is based on a sample survey of 40,000 people, called the British Crime Survey (BCS), which was introduced because of concerns that many people did not bother to report crime.
Both have their limitations.
The British Crime Survey only takes place every year, and does not record crimes which are serious but too small statistically to measure (such as murder and rape) or crimes committed against businesses (such as fraud or shoplifting) or against people under 16 (since it only surveys adults).
The police recorded crime figures - which are produced every 3 months - can be inconsistent between different police forces, and comparisons have suffered because of changes in recording procedures.
For example, the police are now required to note each separate assault when there is a pub brawl as a separate offence, rather than one crime.
The two methods of measuring crime produce different long-term trends.
The BCS, which started in 1981, suggests that total crime peaked in 1995, and has been falling steadily since Labour came to power.
The latest British Crime Survey suggests that the overall level of crime has declined from 12,088,000 crimes in 2003 to 10,811,000 in 2004 (down from around 16m in 1997, a fall of 33%). Violent crime was also down by 10% on this measure.
However, the level of violence against the person recorded by the police rose by 10% in the three months Oct-Dec 2004 compared to the same period one year before, and more serious offences (including murder and serious wounding) were up by 4%.
BCS interviews Jan-Dec 2004
Police records Oct-Dec 2004
Comparisons with previous year
And firearms offences, including those using replica weapons, were up 10%.
Overall, police recorded crime rose from 5.1m in 1998 to 5.7m in 2004, an increase of 17%
So both sides can cite figures to prove their case.
However, it is also significant that the fear of crime has fallen much less sharply in the BCS than actual crime, and there have been no changes in the perceived level of anti-social behaviour.
Most experts would accept that overall, the rate of crime is going down. But certain types of violent crime of particular concern to the public are rising, according to the official recorded crime figures.
While the figures may produce some confusion, it is the fear of crime that all political parties are seeking to address with their plans for increasing numbers of police and additional plans to tackle anti-social behaviour.