The solutions to these problems begin with the positive actions for counting crime more usefully. They end with the ways not to count crime, with the steps governments should take to terminate current practices that hinder all efforts to create greater public safety.
Seven Statistical Series for Counting Crime Usefully
The following seven statistical series are the essential tools needed to count crime usefully, based entirely on reports to and by the police. The seven systems exclude victimization surveys, such as the Crime Survey for England and Wales (CSEW). Such surveys are very useful as a track on crimes reported to police. Yet they are too expensive for taxpayers to fund such surveys in every community and with sample sizes large enough to measure the rarest crimes, which cause the highest harm. The seven also exclude alternative measures of violence from local communities, including ambulance response data and treatments in hospitals or accident and emergency rooms. Those measures are also useful but require further funding and regulation to be established.
These seven statistical series are all inexpensive to create and report, since they rely on existing systems of data collection and reporting. They achieve their success by re-arranging the existing statistical systems in a way that is more informative to the public and more useful for the police:
A Crime Harm Index (CHI)
A crime count by all crime categories
An Historic Offences Crime Harm Index (HOCHI)
A Proactive Policing Index (PPI)
A Company-Detected Crime Harm Index (CDCHI)
A Harm Detection Fraction of total CHI (HDF)
Detection rates per 100 by all crime categories
This section describes each of the statistical series, in a sequence from citizen-reported crimes (“A Crime Harm Index” through “A crime count by all crime categories”) to proactively detected crimes (“A Proactive Policing Index” and “A Company-Detected Crime Harm Index”) to reactive detections of citizen-reported crimes (“A Harm Detection Fraction of total CHI” to “Detection rates per 100 by all crime categories”).
A Crime Harm Index
Wherever a total count of offences is reported, with or without a rate per 1000 people, a Crime Harm Index derived from sentencing guidelines will be reported in place of that count.
The Cambridge Crime Harm Index (CCHI) that demonstrates this method has been provided by the University of Cambridge using this method since 2016, based on the Guidelines for sentences published by the Sentencing Council of England and Wales.Footnote 3 The CCHI takes the number of days of imprisonment recommended as the “starting point” for sentencing decisions before taking into account the aggravating and mitigating circumstances for each case. This is, in effect, a sentence recommendation for a first offender whose crime featured neither aggravation in the act nor mitigating factors since the act (such as attending a restorative justice meeting with the crime victim).
Once each crime category (of over 700 listed on the Cambridge website)Footnote 4 in any jurisdiction is given a CHI score, the number of reported crimes (for 1 year) in each crime category is multiplied by that score (taken from Sentencing Guidelines). The result is a total CHI score for each crime category.
Once the CHI total for each crime category for 1 year (or other time period) is calculated, all of those totals across all of the categories are summed. The sum equals the total CHI score for the jurisdiction for that time period. Identical procedures could be taken within different jurisdictions (such as all 43 territorial police forces in England and Wales) or over time by years, quarters or other time periods.
An example of how the CHI is calculated can be taken from a hypothetical village, which in one year suffered the following count of crimes by category:
100 bicycle thefts
20 burglaries
2 murders
Total = 122 crimes
With this count, the CHI can be calculated by multiplying the number in each category by the Sentencing Council of England & Wales “starting point” guidelines for days of imprisonmentFootnote 5 as follows:
Crime Type × Guideline CHI Score
100 Bicycle Thefts x 2 days = 200
20 Burglaries × 19 days = 380
2 Murders × 5475 days = 10,950
Total CCHI score in days of recommended custody = 11,530
This method would not replace the crime-category counts; it would supplement and apply those counts in computing CHI scores. The only statistics the CHI would replace would be a summary count of all categorical counts—the offence rate per capita or raw number of offences. (Note: The CHI could also be divided by population or by numbers of police officers, for a CHI rate. But the complexity of a CHI rate may be inadvisable in the short run, since the first step in introducing a CHI in place of an offence count is to achieve public understanding and comprehension.)
It is essential that the CHI not include crimes generated by proactive investigations by police or corporations, for reasons discussed in the “Proactive Policing: Outputs, not Outcome” and “Historic Offences: then, not now” sections. Nor should it include crimes that occurred before the time period being measured, even if they were reported in that time period (see the “Detections by Crime Category: Statistics Out of Context” section).
Categorical Offence Counts (a Crime Count Within, but not Across, All Crime Categories)
This recommendation is simple: to continue all of the annual counts of crimes reported in each crime category. These counts are the core data for any Crime Harm Index. Their publication allows any citizen, journalist or police professional to calculate the elements and final result of any CHI by hand from published data. This transparency is a key part of making any CHI legitimate. The only change to current practice would be to remove crimes that are reported through
Historical crimes from prior years reported in the current year
Proactive policing by police
Proactive private policing by companies and other organisations
The three latter categories are all better reported in their own separate statistical series.
An Historic Offences Index
This statistical series would include every crime reported to every police force for which the date of occurrence was prior to the year in which the report is made. It would be calculated in the same way as the CHI for current year crimes. Once each historical crime is counted by a jurisdiction in each category of crime types (of over 700 listed on the Cambridge website, or its equivalent in other countries)Footnote 6, it is given a CHI score, and the number of reported crimes (for 1 year of reporting) in each historic crime category is multiplied by that score (taken from Sentencing Guidelines). The result is a total HOCHI score for each crime category as newly reported that year.
Once the HOCHI total for each crime category for 1 year (or other time period) is calculated, all of those totals across all of the categories are summed. The sum equals the total HOCHI score for the jurisdiction for that time period. Identical procedures could be taken within different jurisdictions (such as all 43 territorial police forces in England and Wales) or over time by years, quarters or other time periods.
In principle, this HOCHI (and its component crime counts) could be used to revise, continually, the previously reported statistics for crimes known to have occurred in those years. This would allow a 10-year crime trend to be reported annually with the more accurate count of crimes in the prior year taken into the calculation of the trends. These adjustments could be made both nationally and locally at any level of geographic breakdowns.
The HOCHI for any current year would be an important recognition of the added workload for police. If, for example, in a flood of new reports about historic sex crimes against children the HOCHI were to equal as much as 15% of the value of the current year’s CHI, that would be an important fact to consider in budget reviews for police forces and resource allocation within police agencies. Such consideration does not, however, require a threat to the reliability of measuring crime trends on the basis of when each crime occurred, nor when it was reported.
A Proactive Policing Index
This statistical series is computed by multiplying the sentencing guideline starting point times each offence detected by police through police-initiated activity, rather than by response to a citizen complaint of a crime. While some items of criminal intelligence might be seen to make proactive policing more ambiguous as to how it was generated, existing systems for distinguishing intelligence from crime reports would be sufficient in countries like the UK. As the Cambridge CHI provides, entire categories of crime are excluded from the CHI, and can be aggregated in a Proactive Policing Index based on CHI metrics.
The procedure for calculating a PPI is almost identical to that for a CHI. Once each proactively detected crime categoryFootnote 7 in any jurisdiction is given a CHI score, the number of reported crimes (for 1 year) in each crime category is multiplied by that score (taken from Sentencing Guidelines). The result is a total CHI score for each PPI crime category, now called a PPI score.
Once the PPI total for each crime category for 1 year (or other time period) is calculated, all of those totals across all of the categories are summed. The sum equals the total PPI score for the jurisdiction for that time period. Identical procedures could be taken within different jurisdictions (such as all 43 territorial police forces in England and Wales) or over time by years, quarters or other time periods.
Calculating a PPI score would be an essential first step towards constructive public dialogue about how much police should invest in low-harm volume crimes reported by citizens, versus high-harm hidden crimes that only police efforts can detect. In England and Wales, this dialogue has already been launched, although with minimal quantification so far. Her Majesty’s Inspectorate of Constabulary, Fire and Rescue Service (HMICFRS) requires that police force management statements contain a strategic plan for discovering unreported “hidden” demand, including crimes with very high levels of harm by sentencing guidelines. That plan could be a means for setting goals on the basis of CHI levels detected, including (and primarily) those cases brought to justice.
The PPI would also include identifications of offenders committing such publicly visible offences as drink driving, speeding, running red lights and other dangerous driving. The creation of a separate reporting statistic for such detections as outputs rather than outcomes could even shape police resource allocation, given the high levels of harm associated with accidents due to criminal negligence. If police efforts were clearly separated from the counting of the CHI, there would be even more incentive to generate new crime reports by making arrests proactively in areas like drugs, modern slavery and people trafficking.
A Company-Detected Crime Harm Index
This statistical series is computed by multiplying the sentencing guideline starting point times each offence detected by an organization and reported to police, as distinct from offences reported by to an individual (not acting on behalf of an organization) as a victim of or witness to a crime. This can be done without too much difficulty by focusing on the name of the complainant. Thus when a shop assistant is threatened at knifepoint and calls police, the shop assistant becomes the victim, and the crime would remain in the CHI list. But when a service station clerk reports that someone has filled a car with petrol and driven off without paying, the oil company becomes the victim and not the clerk. These entire categories of crime can be excluded from the CHI because they do not reflect a level of public safety and can be aggregated in a Company-Detected Crime Harm Index based on CHI metrics.
A Harm Detection Fraction
This statistical series requires, first, the calculation of a total Crime Harm Index for a jurisdiction, which provides a denominator for the harm of all crimes reported to police by victims and witnesses. The next step is to take the currently reported numbers of crimes in each category that were detected in the same time period, by some definition. Countries vary substantially in their definitions of detections, but the key to reliability is consistency of definition within any one country. Within England and Wales, the concept (and list) of agreed-upon sanctioned detections is well-established, including prosecutions, cautions and other acts that generally create a criminal record for the offender.
The next step is to divide the detections by the number of crimes reported, to compute a detected fraction for each crime category. That fraction is then to be multiplied by the total CHI score for that category, which would show the total CHI score for the detections in that category. The final step is to sum the detected CHI scores across all offence categories, and divide that total by the total CHI score of all reported crime. This can be expressed in both the absolute level of the detected score, as well as in the percentage of all reported CHI that was detected.
The time period between reporting and clearance is not a simple matter to address in creating an HDF. Investigations take months and sometimes years to complete. Police practices cannot be driven by statistical reporting requirements. Two simple counting rules will ease the reporting of the HDF. One is to keep a running updated statistic of the number of detections achieved for all the offences reported in each year. The other is never to count as a detection an action taken in 1 year about an offence that occurred in a prior year. Only the use of modern IT systems for tracking running totals of detections for crime and CHI by year of occurrence can save the HDF system from unreliability due to ambiguity.
Detection rates per 100 offences for all crime categories
For reasons discussed in the “Detections by Crime Category: Statistics out of Context” section, it is essential to continue reporting the raw detection rates per 100 offences despite the addition of an HDF. The raw rates are the materials from which the HDF scores must be constructed, in the context of the total CHI scores. They are also a subject of great public interest and should be made as easy to find as possible—like all seven of these statistical series.
Three Ways NOT to Count Crime
This section reiterates points made above, for absolute clarity. The three ways this statement calls on governments not to count crime are totals of reported crimes, total detection rates and average sentences for each offence.
No “Offence Rate”
The first step towards reliable measurement of public safety is to discontinue official computation or reporting of an “offence rate per 1,000 population,” while continuing to report counts for specific offence categories. This step will ensure a public focus on what matters, which is the harm level of crime. By including total offences by crime category, it would still be possible for any reader to create a total. But that computed total would lack the official endorsement of the government for a misleading statistic. In emphasizing the bottom line of a single measure of crime, the government would establish a fair system for letting each police force decide how best to improve public safety—as long as it reduces or controls CHI.
No Total Detection Rate
For the same reason, there should be no endorsement of a total detection rate across all reported crimes. The total detection rate would keep a spotlight on minor crime, and divert visibility from major crime. The Harm Detection Fraction should be given primacy (after CHI itself) in media discussions of crime and policing, including ratings of police forces for their percentage of CHI that is detected (HDF) after adjustment for population and historical crime levels.
No Average Sentences
The severity rating of any crime type should be based solely on the harm of the crime; it should not reflect the prior record of the offenders convicted of that crime type. Actual sentencing data are heavily weighted by the prior record of the offender. The Office of National Statistics should rely on the “starting point” sentence for each crime category recommended by the Sentencing Council for England and Wales.