How Kent Police uses algorithms to triage cases


A police force in the UK is using an algorithm to help decide which crimes are solvable and should be investigated by officers. As a result, the force trialing it now investigates roughly half as many reported assaults and public order offences.

This saves time and money, but some have raised concerns that the algorithm could bake in human biases and lead to some solvable cases being ignored. The tool is currently only used for assessing assaults and public order offences, but may be extended to other crimes in the future.

When a crime is reported to police, an officer is normally sent to the scene to find out basic facts. An arrest can be made straight away, but in the majority of cases police officers use their experience to decide whether a case is investigated further. However, due to changes in the way crimes are recorded over the past few years, police are dealing with significantly more cases.

The Evidence Based Investigation Tool (EBIT) instead uses an algorithm to produce a probability score of a crime’s solvability. Kent Police, which has previously experimented with using algorithms, has been using EBIT for a year to assess the solvability of assaults and public order offences, such as threatening someone in the street. These types of offences account for around a third of all crime in the area.

Before the force began using EBIT, officers decided to pursue around 75 per cent of cases. This has now dropped to 40 per cent as a result of the algorithm, while the number of charges and cautions has remained the same, according to Kent Police.


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Photo credit: xiaohaohao, flickr.