Juristat Bulletin—Quick Fact
Understanding and using the police-reported Crime Severity Index

Statistics Canada releases data and analysis on crime and justice throughout the year. The police-reported Crime Severity Index (CSI) is one important way of looking at crime. The CSI is a summary measure of the volume and severity of police-reported crime in an area. It is also a standardized and consistent measure which complements the conventional crime rate and self-reported victimization data.

In response to feedback from different communities, Statistics Canada recognized the need to provide more comprehensive context on this important measure. Statistics Canada wants to ensure that users have the necessary tools to understand and interpret the CSI with respect to the unique circumstances of a given community.

Meaningful engagement with Indigenous and local community stakeholders, and local government representatives, reinforced the importance of presenting the CSI as a nuanced tool that requires careful interpretation. Specifically, the feedback highlighted the risk of oversimplifying crime data and the potential for misleading comparisons between different communities with distinct social, economic, and demographic contexts.

As a result, three new products were developed to highlight the origins of the CSI and the importance of interpreting it in conjunction with other data sources to better understand crime in an area.

These products were published alongside the July 2024 release of police-reported crime statistics for 2023. They reflect a commitment to addressing stakeholder needs, improving data accessibility and coherence, and providing information that empowers data users to interpret the CSI with confidence.

The three new products included:

• Understanding and using the Crime Severity Index
• Infosheet: Understanding and using the Crime Severity Index
• Video: A look at the Crime Severity Index

In addition to these products, on July 17, 2024, Statistics Canada held two Canada-wide webinars exploring the CSI and describing the importance of interpreting it in a broad community context. Each webinar also instructed users on how to access relevant online data products and resources related to crime and justice information.

The origins of the Crime Severity Index

Since the 1960s, police-reported crime from the Uniform Crime Reporting Survey (UCR) has been understood through the conventional crime rate, which considers the number of federal statute offences per 100,000 population, regardless of the nature of those offences.

The Crime Severity Index (CSI) was developed in 2009 as a complementary measure to the conventional crime rate and self-reported victimization data. It represented the first major change in how Statistics Canada looked at police-reported information in nearly 50 years.

The CSI is a standardized and consistent measure of crime and a key indicator for sustainable development^Note  and quality of life^Note  in Canada. It is intended to be one of many sources of information that can be used to better understand the evolving nature of crime in Canada.

Measuring police-reported crime with the Crime Severity Index

The conventional crime rate measures the total number of crimes reported by police in an area relative to its population. Each crime has the same impact on the crime rate—for example, one murder has the same impact on the crime rate as one theft.

Typically, more frequent but less serious crimes have the largest impact on the crime rate.

While this is a useful measure of crime volume over time, it is less effective at reflecting changes in less frequent crimes, even if they are more serious.

The CSI was developed to address the limitations of the conventional crime rate by looking at both the number and relative seriousness of crimes to create an index, and then track these changes over time.

Measuring—or weighing—crime severity

The CSI looks at both the number and the relative seriousness of crimes. To calculate the CSI, each type of crime is assigned a weight that represents its relative severity. To calculate the actual weight for an offence, the incarceration rate for that offence—that is, the percentage of all convictions receiving a jail sentence—is multiplied by the average length of the prison sentence in days (incarceration rates and average prison sentences are calculated at the national level using five years of courts data). Then, the number of police-reported incidents for a given type of crime is multiplied by the crime's weight. Assigned weights are based on standardized information from court sentencing data over the previous five years.^Note 

Crimes that are more likely to result in prison time and longer sentences are given a higher weight.

So, for example, first-degree murder has a far heavier weight in the CSI than property theft, highlighting its severity, even though it happens far less frequently. Relative to the conventional crime rate, the CSI will better reflect the impact of a change in the frequency of first-degree murder, whereas with the conventional crime rate, this change may go undetected.

Why do we use the CSI?

Extensive consultation and development work ensures the CSI is methodologically sound, easily understandable, and robust with respect to changes in crime.^Note 

The CSI is one important way of looking at crime, however, the CSI is not intended to be used in isolation and is not a universal indicator of community safety. Other sources of key information include detailed census profiles, as well as crime and justice data and analytical articles available through the Crime and Justice Statistics Portal.

The CSI is one piece of a much larger puzzle that helps Canadians better understand the country—its population, resources, economy, environment, society and culture.

For additional contextual information within and outside the criminal justice system, see the following resources:

• Crime and justice statistics
• Census Profile, 2021 Census of Population
• Centre for Municipal and Local Data
• Rural Canada statistics