Section 1: The Crime Severity Index

Each year, Statistics Canada reports on the number and type of criminal incidents coming to the attention of police. This annual report analyses changes in police-reported crime rates across the country. To facilitate comparisons among geographic areas as well as over time, police-reported crime has traditionally been expressed as a rate per 100,000 population.

The traditional "crime rate" provides information on the number of police-reported incidents that have occurred for a given population. It measures the volume of crime coming to the attention of the police. The rate is simply a count of all criminal incidents reported to and by police divided by the population of interest. Each criminal incident, regardless of the type or seriousness of the offence, counts the same in the rate. For example, one homicide counts the same as one act of mischief.

A new, additional tool has now been developed for measuring police-reported crime in Canada. The Crime Severity Index will, for the first time, enable Canadians to track changes in the severity of police-reported crime from year to year. It does so by taking into account not only the change in volume of a particular crime, but also the relative seriousness of that crime in comparison to other crimes.

The Crime Severity Index helps answer such questions as: is the crime coming to the attention of police more or less serious than before; and, is police-reported crime in a given city or province more or less serious than in Canada overall?

The new Index does not replace, but rather complements, existing measures of crime. It provides a different way of looking at crime and addresses some of the limitations of the traditional crime rate.

The background

In 2004, the Police Information and Statistics Committee of the Canadian Association of Chiefs of Police asked Statistics Canada to create a new measure of police-reported crime that would address the limitations of the traditional crime rate.

The traditional crime rate is heavily influenced by fluctuations in high-volume, less serious offences. This is because each offence reported by police, regardless of its seriousness, carries exactly the same weight in calculating the crime rate.

About 40% of police-reported crime in Canada comes from two relatively less serious offences: thefts under $5,000 and mischief. Any change in the number of these offences reported by police will have a significant impact on the overall crime rate.

If the number of minor thefts and mischief both decrease in a given year, the crime rate is likely to decline, even with significant increases in more serious crimes such as murder and break-ins. In other words, because of their relatively low volume, more serious crimes have little impact on changes in the overall crime rate.

Variations in reporting crimes have long been a fundamental limitation of using police-reported data to understand trends and make comparisons among jurisdictions. Victimization data have consistently shown that reporting to police is related to the seriousness of the offence. Less-serious offences, which dominate the crime rate, are more likely to go unreported to police. 1  In turn, these offences are not always reported consistently by police to Statistics Canada. These reporting issues have had an impact on the comparability of crime rates among provinces, territories and police services.

The traditional crime rate does not provide information on the overall seriousness of crimes reported by police. Historically, changes in the seriousness of police-reported crime have been assessed by reviewing offence-specific crime rates. However, it is difficult to create an overall picture of trends in crime severity using this approach.

The Crime Severity Index was designed in collaboration not only with the police, but also with provincial and territorial justice partners and academics across the country. 2  A working group was given a mandate to create a measure that would provide a more meaningful indicator of change in police-reported crime from year to year, and which would enhance the comparability of crime statistics at the provincial, territorial and municipal level by taking into account the relative seriousness of each offence.

Designing the Crime Severity Index

The principle behind the Crime Severity Index was to have more serious crimes carry a higher weight than less serious crimes. As a result, changes in more serious crimes would have a greater impact on the Index than on the traditional crime rate.

This would reduce the impact of high-volume, less serious offences and allow the Index to better reflect changes in the incidence of more serious crimes. It would also minimize the impact of differences in the way the public and police in various jurisdictions report high-volume, less-serious crimes, thereby improving comparisons among provinces and municipalities.

The first step in the development of the Index was to find a way to assess the relative seriousness of crimes. Any such measure had to meet specific criteria. Namely, it had to be as empirical and objective as possible. It also had to be based on existing data, easy to update over time, and easy to understand. Further, the Index was to include all reported crimes, unlike the traditional crime rate which excludes traffic and drug offences as well as Federal Statutes.

A detailed review of criminological literature provided a number of existing approaches for determining the relative seriousness of different crimes. Various options were explored: including only a subset of the most serious crimes; using information on public perceptions of crime; looking at the financial cost of crime; and, using maximum penalties outlined in the Criminal Code. However, none of the existing methodologies met all the criteria set out.

In the search for another approach, it became apparent that data collected from Statistics Canada's surveys of adult and youth criminal courts 3  met all the criteria for defining a measure of relative seriousness. Canada is one of the few countries that collects extensive sentencing data from the court system.

The underlying premise of sentencing is that more serious crimes will receive more serious punishments from the courts. Thus, the relative seriousness of each type of criminal offence can be determined by using objective sentencing data. These data already exist and are collected regularly, so updates can be made to the measure of relative seriousness over time.

How the Index is calculated

The Crime Severity Index tracks changes in the severity of police-reported crime by accounting for both the amount of crime reported by police in a given jurisdiction and the relative seriousness of these crimes. It tells us not only how much crime is coming to the attention of police, but also about the seriousness of that crime.

To do this, each type of offence is assigned a seriousness "weight". 4  The weights are derived from actual sentences handed down by courts in all provinces and territories. 5  More serious crimes are assigned higher weights, less serious offences lower weights.

The specific weight for any given type of offence consists of two parts. The first component is the incarceration rate for that offence type. This is the proportion of people convicted of the offence who are sentenced to time in prison. The second component is the average (mean) length of the prison sentence, in days, for the specific type of offence. 6 

Offences that tend to be subject to incarceration upon conviction are generally considered more serious than those that are not. Further, more serious crimes generally receive longer custodial sentences. The incarceration rate is multiplied by the average sentence length to arrive at the final seriousness weight for each type of offence reported by police.

Each occurrence of a particular offence is assigned the same weight regardless of the specific outcome of any individual case. For example, all robberies reported by police carry the same weight in the Index, regardless of the specific characteristics of each incident.

The weights are calculated using the five most recent years of available sentencing data. This ensures that there is a large amount of data available on which to base the weights. It also minimizes the impact of any fluctuations for low-volume offences. For the data released in this report, weights are based on the period 2002/2003 to 2006/2007.

Table 1 provides examples of the specific weights based on court data for this period. The importance of the weights is not so much in their exact value for each offence, but rather in the relative differences between them. For example, an incident of murder would receive a weight 1,000 times higher than an incident of possession of cannabis.

The weights will be updated every five years to ensure that they reflect any changes in sentencing patterns or new legislation. It is not necessary to update them each year as trends in court data do not tend to change substantially from year to year.

To calculate the actual Crime Severity Index, the number of police-reported incidents for each offence is multiplied by the weight for that offence. 7  All weighted offences are then added together and divided by the corresponding population total.

Finally, to make the Index easier to interpret, the Index is standardized to "100" for Canada (a system that is similar to the Consumer Price Index), using 2006 as a base year.

Challenges of using sentencing data as a measure of offence seriousness

Statistics Canada collects sentencing data from both youth and adult courts across the country. When it was decided that these sentencing data were the best available empirical measure of offence seriousness for the Crime Severity Index, the limitations of these data were also recognized. Examples of some of the challenges posed by the courts data include:

Time served on remand– Time served in remand – the amount of time an accused person spends in jail prior to sentencing – is not directly collected by the courts surveys. Although the length of time served in remand is generally factored into the sentence by judges, it cannot be determined from the survey data if the full sentence has been recorded (including days spent in remand) or if just the additional time to be served has been recorded (excluding days spent in remand).

Repeat offenders– The previous criminal record of an accused person is known to be a significant factor in sentencing; however, data on recidivism is not available from the courts surveys.

Conditional sentences– Conditional sentences, also called "deferred custody" for youth, were treated as "non-incarceral" in the model, similar to sentences of probation or fines, even though the Criminal Code considers them to be a sentence of incarceration. This was done because no systematic and objective system exists for determining relative seriousness among different types of sentences.

Life sentences– Life sentences in Canada are a custodial sentence for the rest of the natural life of the accused. As such, life sentences cannot be accurately measured in terms of days as it depends on a number of factors specific to the individual. For research purposes it is generally agreed to be quantified as 25 years, which represents the longest parole eligibility for an individual sentenced to life. Following parole, the accused remains under supervision for the remainder of their natural life. Life sentences thus were assigned a value of 25 years for the purposes of the Crime Severity Index weighting model.

There will, in fact, be three indexes – an overall Crime Severity Index, a Violent Crime Severity Index and a Non-violent Crime Severity Index – similar to the structure of the traditional crime rate.

The overall Crime Severity Index includes all Criminal Code and federal statute offences. The Violent Crime Severity Index includes all violent offences, 8  while the Non-violent Crime Severity Index includes everything that does not fall into the category of violent offences.

Each index can be calculated at the national, provincial/territorial and census metropolitan area 9  levels, as well as for individual police services and detachments.

By design, the specific Crime Severity Index value in a given jurisdiction depends on its mix of crimes and their relative seriousness. If a jurisdiction has a high proportion of less serious, and hence lower-weighted, offences, it will have a lower Index value. Conversely, a jurisdiction with a high proportion of more serious crimes will have a higher Index value.

Understanding crime trends with the Crime Severity Index

It is important to understand a few things before comparing the Crime Severity Index and the traditional crime rate. First, one can only compare trends in police-reported crime indicated by these two measures. The specific levels of police-reported crime provided by each measure are not directly comparable.

Secondly, the Crime Severity Index is expressed as a standardized measure, meaning it has been adjusted to equal 100 in the base year (2006). On the other hand, the crime rate is expressed as the number of crimes per 100,000 population. As such, all graphs showing the two measures appear with two separate axes, one for the crime rate and another for the Crime Severity Index.

Comparisons between the overall crime rate and the Crime Severity Index between 1998 and 2007 provide interesting insights into trends in overall police-reported crime (Chart 1.1 and Table 2 10  ). During that period, the crime rate decreased by 15%, while the Crime Severity Index dropped even further (21%). It should be noted that while drugs, traffic offences and Federal Statutes are all excluded from the traditional crime rate, they are included in the Crime Severity Index.

Thus, not only was the volume of police-reported crime in Canada declining during this period, but overall, crimes coming to the attention of police were less serious in nature. Further, the severity of crime, as reported by police, declined at a faster rate over this decade than did the number of crimes reported.

In most years, the crime rate and Index moved in the same direction. However, between 1999 and 2002, they did not. During this period, there was virtually no change in the amount of overall crime reported to police, as indicated by a stable crime rate. However, the Crime Severity Index dropped by 6%.

During this time, the volume of several serious crimes fell significantly, such as break-ins (-16%) and robbery (-11%). At the same time, there was an increase in reported incidents of mischief (+3%), which is a high-volume, but relatively less serious offence.

The conclusion is that between 1999 and 2002, the amount of overall crime reported by police remained stable, but there was a drop in the severity of crime coming to the attention of the justice system. This example demonstrates how the Crime Severity Index better reflects changes in more serious offences, while the crime rate reflects the overall volume of crime coming to the attention of police.

In Table 3, data clearly show the differences between the two series. Theft under $5,000 accounts for 26% of all crimes in the crime rate. Weighting these crimes for seriousness in the Crime Severity Index effectively decreases their contribution by slightly more than half, to 12%. Conversely, breaking and entering, a high-volume offence that carries an above-average seriousness weight, makes up about one-quarter of the Index's weighted volume, compared with 10% in the crime rate. Robberies contribute 1% of the crime rate, but 11% of the Index.

Separate severity indexes have been created for violent and non-violent crimes. Comparing the rates and indexes for these types of crimes further demonstrates the utility of each source of information for understanding trends in police-reported crime.

For example, the violent crime rate rose between 1998 and 2000, then declined afterwards (illustrated by Chart 1.2). This indicates that the volume of violent crimes reported by police has been falling since 2000. Meanwhile, the Violent Crime Severity Index indicates that the severity of violent crimes reported by police remained relatively stable during the period.

Of particular interest is the period between 2004 and 2006 when the violent crime rate and Violent Severity Crime Index moved in different directions. During this period, the violent crime rate declined slightly despite increases in most serious violent crimes, including attempted murder (+22%), level 3 assault (+20%), level 2 assault (+12%) and robbery (+10%). The drop in the violent crime rate was driven by a decline in level 1 assault, the least serious form of assault, but a high-volume offence. Conversely, the Violent Crime Severity Index rose 4% during this period, reflecting increases in more serious violent crimes.

Data in Table 4 show the relative contributions of crimes comprising the Violent Crime Severity Index and the violent crime rate. While level 1 assaults, the least serious form of assault, account for the largest share (about 40%) of the violent crime rate, they comprise only 9% of the Violent Crime Severity Index.

Robbery comprises the largest share of the Violent Crime Severity Index (40%), but a much lower share of the violent crime rate (8%). Homicide accounts for 8% of the Violent Crime Severity Index, compared with less than 1% of the violent crime rate.

In terms of non-violent crime, trends in the two measures were similar between 1998 and 2007 (Chart 1.3). However, the 18% decline in the rate of non-violent crimes was less than the 26% decline in the Non-violent Crime Severity Index. This shows that the more serious non-violent crimes were dropping at a faster rate than the less serious offences.

For example, breaking and entering, which has an above-average weighted seriousness, fell by 40% over this time, while theft under $5,000, with a lower–than-average weighted seriousness, dropped 26%.

Data in Table 5 show the relative contribution of crimes comprising the Non-violent Crime Severity Index and the non-violent crime rate. The largest contributor to the Index was breaking and entering, accounting for 35%, while it comprised only 13% of the non-violent crime rate.

Theft under $5,000 was the largest contributor of all crimes to the non-violent crime rate (32%), but comprised only 17% of the Non-violent Crime Severity Index. The impact of other less serious non-violent crimes is also minimized in the Non-violent Crime Severity Index. For example, the contribution of mischief to the Index was only half of its contribution to the rate.

Provinces and territories

The Crime Severity Index is also a tool for measuring the increase or decrease in the severity of crime over time in any given jurisdiction, such as provinces and territories, and for comparing the seriousness of crime among jurisdictions.

Over time, police-reported crime rates have generally been higher in the west and north than in eastern and central regions of the country. This is also true for crime severity, as measured by the new Crime Severity Index (Chart 1.4 and Table 6). There are, however, some important differences when comparing jurisdictions using the two measures of police-reported crime.

First, as illustrated by Chart 1.4, the Crime Severity Index in the three territories is much closer to the indexes for the provinces than is the crime rate.

Crime rates in the three territories are about 60% to 230% higher than the crime rate for the highest province. In terms of the Index, the gap is much smaller. Crime Severity Indexes for all three territories are only about 15% to 100% higher than the Index for the highest province.

This suggests there is less difference between the provinces and territories in the severity of crime reported to police than in the amount of crime being reported. The reason is the mix of crimes reported in the North. A higher proportion of less serious crimes are reported in the territories than in the rest of Canada. For example, mischief accounts for 29% of all reported crimes in the three territories combined, nearly twice the proportion of 15% for the provinces overall.

In 2007, Saskatchewan had the highest Crime Severity Index among the provinces. Its severity index value for 2007 was 165, compared with 95 for Canada as a whole. This indicates that the severity of police-reported crime in Saskatchewan was about 75% higher than for the entire nation.

Crime severity in Saskatchewan, however, dropped by 7% between 1998 and 2007. Manitoba and British Columbia, the provinces with the next highest Crime Severity Index values, also experienced drops in crime severity between 1998 and 2007 (-3% and -22% respectively). In all three provinces, the declines occurred predominantly between 2003 and 2007.

Ontario and Quebec have had the lowest police-reported crime rates in recent years. When the severity of crime is considered, however, Prince Edward Island and New Brunswick have the lowest Index scores. While there may be less crime coming to the attention of police in Ontario and Quebec after adjusting for population differences, reported crime in these provinces is relatively more serious than in Prince Edward Island and New Brunswick.

Chart 1.5 illustrates differences between the provinces in violent crime. Violent crime rates in the western and northern regions tend to be higher than those in eastern and central Canada. Again, however, territorial values for the Violent Crime Severity Index are much closer to the provinces than violent crime rates. And again this is due to the mix of violent crimes in the North. The territories have a higher proportion of less serious violent crimes, such as level 1 assault, than the provinces.

While Saskatchewan has the highest violent crime rate among the provinces, Manitoba has a slightly higher Violent Crime Severity Index value. This is due to the high proportion of serious violent crimes, such as robbery and level 2 and 3 assaults, reported in Manitoba. The severity of violent crime in Manitoba was 12% higher in 2007 than it was in 1998.

Chart 1.6 compares the provinces and territories in terms of their non-violent crime rates and their non-violent Crime Severity Indices. Non-violent crime rates tend to be higher in the western and northern regions of Canada. The same is true for the severity of non-violent crime. In 2007, Saskatchewan had the highest Non-violent Crime Severity Index value among the provinces, at 163, followed by Manitoba (141). The lowest Non-violent Crime Severity Index values were in Ontario (70), Prince Edward Island (72) and New Brunswick (72).

Census metropolitan areas

The Crime Severity Index is also a useful tool for comparing the severity of crime among large metropolitan areas (Chart 1.7 and Table 7).

In 2007, the severity of crime was highest in Regina. It had a Crime Severity Index of 189, nearly twice the national average of 95. Crime severity in Regina was, however, down 18% from 1998. Regina was followed by Saskatoon (159) and Winnipeg (153). Saskatoon saw a drop of 12% in overall crime severity since 1998 due mostly to a 51% decrease in break-ins. On the other hand, the Crime Severity Index in 2007 was lowest in Toronto, Saguenay and Québec (all at 66), and Kitchener and Trois-Rivières (both at 69).

In terms of violent crime a somewhat different pattern emerged, as illustrated by Chart 1.8. Index values for violent crime in the many large metropolitan areas in central Canada were closer to average. In Toronto, the Violent Crime Severity Index was 95, virtually equal to the national average. The severity of violent crime was above average in Montreal (108).

The Crime Severity Index can be used to point out unusual regional characteristics of crime. In general, crime is less severe in the Atlantic Provinces than for Canada as a whole. But this does not necessarily hold for the country's largest metropolitan areas. In 2007, all three metropolitan areas in Atlantic Canada had Index values above the national average of 95: Saint John (107), Halifax (106) and St. John's (100). This indicates that police-reported crime in these cities tends to be of a more serious nature than in central Canada where the severity of crime in many central Canadian metropolitan areas was below average.

In some Western metropolitan areas, values for the Violent Crime Severity Index were lower than their overall Index values. For example, Victoria had an overall Crime Severity Index value of 109, well above the national average. However, its Violent Crime Severity Index value of 81 was well below the national average. This indicates that while the severity of crime was relatively high in Victoria in 2007, the proportion of serious violent crimes was relatively low.


This analysis has demonstrated how the Crime Severity Index is a useful additional tool for analyzing crime trends in Canada. The Index addresses not only the amount of crime coming to the attention of police, but also the severity of this crime. In addition, it shows whether crime in general is relatively more or less serious than in previous years, and it helps in determining if reported crime is more or less serious in one jurisdiction than in another.

The Crime Severity Index has a number of strengths. It better reflects trends in more serious crimes because it takes into account the relative seriousness of offences. Serious crimes have a greater impact on the Index than they do on the crime rate. It also improves the comparison of trends in crime among police services, provinces/territories and municipalities by reducing the impact of differences in the way less serious offences are reported.