The Cambridge Crime Harm Index (CCHI)
The Cambridge Crime Harm Index (CCHI) is the first system that measures the seriousness of crime harm to victims, and not just the number of officially recorded crimes.
All crimes are not created equal in the harm they cause: homicide is many times more harmful than shoplifting but in crime statistics where offences are counted by number, they appear equivalent. For example, in the UK for the year ending September 2019, there were 3,578,000 incidents of theft and 729 homicides (Office for National Statistics, 2019). An increase of 500 thefts would be a small change in the overall number of thefts and have little impact on police resources. 500 extra homicides would have large consequences both for the harm caused and the impact on police resources. In a number-only count, the additional 500 thefts or homicides would result in the same overall number of crimes, yet clearly the impacts are disparate.
This reality has led to the proposition of a “Harm Index” to measure how harmful different crimes are in proportion to the others. This approach adds a larger weight to more harmful crimes (e.g. homicide, rape and grievous bodily harm with intent), distinguishing them from less harmful types of crime (e.g. minor thefts, criminal damage and common assault). Practically, adoption of a harm index can allow targeting of the highest-harm places, the most harmful offenders, the most harmed victims, and can assist in identifying victim-offenders. Experimentally, use of a harm index can add an additional dimension to the usual measures of success or failure, by considering harm prevented as well as reductions in prevalence or frequency. For the police, creation of harm index could allow them to invest scarce resources in proportion to the harm of each offence type.
The initial paper (Sherman, Neyroud and Neyroud, 2016) outlining the creation of the Cambridge Crime Harm Index (CCHI) is available here.
Sherman, Neyroud and Neyroud (2016) propose that any index needs to meet three requirements in order to be considered a legitimate measure of harm: An index must meet a democratic standard, be reliable and also be adopted at minimal cost to the end user. To meet these requirements, Sherman, Neyroud and Neyroud (2016) opted for using sentence starting points rather than maximum or average actual sentences. The sentencing starting point is used to calculate crime harm as it provides a baseline penalty relative to the crime. We propose that it is a better measure of harm caused by the crime than average actual sentences, which are offender-focused and thus substantially affected by previous offending history.
An initial index of crime harm for England and Wales based on starting point sentences was created, scoring around 700 offences. Offences where the starting point was a set prison sentence were converted into number-of-days imprisonment: for example homicide in England and Wales starts at 15 years, which would give a CCHI score of 5,475. For offences where the starting point is either a community sentence or a fine, scores based on the number of hours needed to complete the unpaid work requirement of the community sentence or hours needed to work to pay off the fine were used. This index has since been updated for 2020 (see link below) and now includes not only the criminal justice codes and home office classifications relevant to identifying each type of crime, but also the unique reference codes used by the ATHENA system, a crime recording and management system used by several UK forces, aiming to improve the ease of adding CCHI scores to existing police data.
The Cambridge Crime Harm Consensus paper (How to Count Crime: the Cambridge Hard Index Consensus) proposes creation of seven statistics for counting crime, usefully including separation of historic crime reports, creation of a harm detection fraction and separation of public reported crime and those detected by proactive police activity, with the aim of providing the public with a more reliable and realistic assessment of trends, patterns and differences in public safety.
A list of academic papers using the Cambridge Crime Harm Index is available via this link.
A list of academic papers discussing Harm Index creation or use in other countries is available below:
- The Danish Crime Harm Index: How It Works and Why It Matters(Anderson & Müller-Johnson, 2018)
- Designing the Swedish Crime Harm Index: an Evidenced-Based Strategy(Kärrholm, Neyroud & Smaaland, 2020)
- Developing a Crime Harm Index for Western Australia: the WACHI (House & Neyroud, 2018)
Queries about the Cambridge Crime Harm Index should be directed to: admin@cambridge-ebp.co.uk