Author: McCormick, Amanda V.
Title: Challenges Associated with Interpreting and Using Police Clearance Rates
Summary: Police-reported crime statistics include frequency of criminal incidents, the severity of incidents, and the solve rate of incidents (Statistics Canada, 2011). These statistics are collected nationally on a monthly basis from over 1,200 different police departments in Canada, and are used to determine the overall crime and clearance rates annually reported to the public in a Statistics Canada document describing trends on a national, provincial, and, at times, municipal basis (Statistics Canada, 2011; Wallace, 2009).
Police-reported crime statistics are collected for Statistics Canada by the Canadian Centre for Justice Statistics (CCJS) through the Uniform Crime Reporting (UCR) Surveys (Wallace, 2009). One survey collects aggregate data, while the other collects incident-based data; specifically, incident and offender characteristics (Statistics Canada, 2003). Importantly, when a single criminal event involves multiple offences (e.g. an intoxicated person who committed an assault in public is found to be holding a small amount of marijuana), the aggregate UCR collects data on only the most serious incident (the assault)1; therefore, the national statistics on crime represents only a portion of the total amount of crime. While the UCR Incident-Based Survey records additional incidents (although detailed information pertaining to the additional offences is not reported), there is a maximum of four violations allowed recorded per incident, meaning that undercounting of criminal incidents occurs (Wallace, Turner, Matarrazo, & Babyak, 2009). Furthermore, data reported to CCJS does not reflect all activities of police, as many calls for service are based on violations of provincial (e.g. Mental Health Act) or municipal (e.g. bylaw issues) legislation.
UCR-based data is further limited in that it does not reflect the dark figure of crime, i.e. the amount of crime not detected, reported to, or recorded by police, nor does it reflect unfounded (crimes that were reported but which did not actually occur) or unsubstantiated (crimes that were reported but police determine there is no evidence to support that an offence occurred) crimes. These offences are not reflected in UCR data, and, therefore, are not factored into crime and clearance rates (Statistics Canada, 2011; Wallace et al., 2009). Instead, UCR data only consists of crimes that have been reported and substantiated by police. Despite these restrictions and limitations, these official statistics are commonly used by policy makers, academics/researchers, and the general public to draw inferences about the effectiveness of various police forces at deterring, investigating, and solving crime, and inform the public about the quantity and nature of crime (Hollins, 2007).
Crime rates are calculated by dividing the number of criminal incidents in a given time period (often the past year) by a given population number (often 100,000 for national statistics or 1,000 for provincial). Thus, the crime rate theoretically allows for meaningful comparisons to be drawn between jurisdictions as the size of the population is controlled. However, using crime rates for this purpose should be done with caution, given the limitations on the types of data included.
Similarly, clearance rates are calculated by dividing the number of solved crimes by the total number of crimes. Theoretically, clearance rates measure the effectiveness of a police force at investigating and successfully solving crimes. According to Statistics Canada, crimes are "solved" when police have sufficient evidence to charge an individual with the offence. These solved offences can then be cleared through a charge or cleared "otherwise", meaning that police had sufficient grounds to lay charges, but proceeded in some other way, such as by diverting the chargeable suspect. These two forms of solving crime are factored into the clearance rate, which, prior to 2009, was calculated by dividing the total number of calls successfully cleared by the total number of known incidents.
The remaining offences not cleared may be left as founded uncleared in that there is evidence that a crime occurred, but not enough evidence to identify a chargeable suspect. Alternatively, the offence may be unfounded or unsubstantiated but, as previously noted, these latter two offence types will not be factored into the crime or clearance rates, as there is insufficient evidence that a crime actually occurred. Calls for service can also be scored as involving assistance, information, or prevention; similar to unfounded or unsubstantiated calls, these do not involve reportable offences and so are not factored into crime or clearance rates. With these non-reportable exceptions to police calls for service, founded uncleared crimes represent the overall number of reportable crimes unsolved by police.
Recently, changes have occurred to both crime and clearance rate calculations to factor in the severity of crimes cleared by police. This is a very important change because, previously, crime rates would be dominated by high volume, but relatively minor crimes. For example, a decrease in the number of thefts under $5,000 could have the effect of decreasing the overall crime rate when more serious crimes, such as assaults, were increasing (Wallace et al., 2009). Thus, in 2009, the Crime Severity Index was introduced so that offences were weighted based on their seriousness.
Similarly, since 2009, clearance rates have also been calculated using a weighting formula that assigns more weight to more serious offences (Wallace et al., 2009). As a result of this weighting system, a national weighted clearance rate of 38% does not mean that police solved 38 out of every 100 recorded crimes. Clearance rate statistics today are therefore not straightforward reflections of how many incidents were cleared relative to how many occurred, making it more difficult to use these statistics for comparative purposes. However, as will be argued below, even prior to the introduction of the weighted clearance rate, using clearance rate data for comparative purposes was problematic for other reasons.
Details: Abbotsford, BC, Canada: University of the Fraser Valley, Centre for Public Safety and Criminal Justice Research, 2012. 46p.
Source: Internet Resource: Accessed November 6, 2013:
Year: 2012
Country: Canada
URL:
Shelf Number: 131599
Keywords:
Crime Statistics (Canada)Incident-Based ReportingPolice-Reported Crime Statistics |
