Interpreting crime and justice statistics

Crime and justice statistics are based on the analysis of information collected by criminal justice agencies for operational purposes. This affects the type of crime and justice statistics that can be produced. Criminal justice agencies include those responsible for preventing and responding to crime, adjudicating offences and the management of people accused or convicted of offences. The following information is important to consider when interpreting crime and justice statistics:
 

• Crime and justice statistics will often refer to both ‘numbers’ and ‘rates’. Looking at rates is important as it takes the size of the population into account when looking at trends, and helps us make sure that any changes in observed numbers are not only due to population changes. The use of rates also means we can compare different demographic groups and geographical locations characterised by different population sizes.
  
  The population information used to calculate rates is based on people who live in a particular area. This means people who are temporarily staying in a location (for example, for work or holiday reasons) are not included in the population information used to calculate rates. However, people temporarily based in a location may commit crimes and offences are recorded against the location they are committed. This means crime rates may be overestimated for areas characterised by a transient population such as those with high levels of fly-in, fly-out workers or tourism.
   
• The application of different counting rules will result in different statistics even if the same criminal justice information is being analysed. There can be genuine reasons for using different counting rules. For example, it can be more important to have information on individuals, rather than offences, if you are responsible for designing criminal justice interventions being delivered to people. The use of different counting rules means taking the time to read the information provided about them will support their reliable interpretation.
   

• Many factors can influence crime and justice trends, and some of these factors may not relate to the actual level of crime taking place. For example, crime rates may increase due to:

  • higher levels of crime detection by police (due to special operations or improvements in technology)
  • operational changes that impact the way information is recorded
  • the expansion of initiatives that support more people reporting crime to police
  • changes to law that result in the introduction of new offences.

  Conversely, crime rates may decrease if police resources are used to support the community during certain events, certain offences become decriminalised, or technological advances enable crime to go undetected. Changes in Queensland’s population profile may also impact crime rates. For example, research has shown that people aged over 65 years are less likely to commit crime than younger people. Therefore, a drop in crime rates may relate to an ageing population. 
  
  These factors can impact different offences and different groups in various ways. That is, while the total crime rate may show a particular trend, this trend may not be apparent for all offences and all offender groups.
   

• The various factors influencing crime trends means there can be a big difference between long–term and short–term crime and justice trends. Looking at longer-term trends helps us understand that trends can fluctuate unexpectedly and that an increase observed at a particular point in time does not mean growth will be apparent for future points in time. The opposite is also true – a drop occurring at a point in time does not mean the decrease will continue. Long-term trends provide a more holistic picture of what is happening than short-term trends.
   
• Looking at percentage change between two points in time is a useful way to summarise trends. However, the size of numbers should be considered when looking at percentage changes. For example, if 10 is added to 10 the percentage change is 100%, but if 10 is added to 100 the percentage change is 10%. That is, small changes to small numbers can seem like large growth.
   
  Understanding how the size of numbers can impact percentage change is also important when making comparisons between different groups. For example, there are many more men than women in contact with the criminal justice system, so caution is required when comparing percentage changes relating to these two groups. There are many other examples: property offences are more common than violent offences; the number of people in remote locations is smaller than the number of people in urban locations; and the number of young offenders (aged 10 to 17 years) is much smaller than the number of adult offenders. 
  
  Small numbers are also more prone to trend fluctuations than large numbers. This means interpreting trends based on larger numbers will be more reliable than those based on small numbers. Small numbers can often occur when information is broken down by multiple factors (such as location, age group, sex and/or Indigenous status).
   

• Crime is subject to seasonal fluctuations, with crime tending to peak in the summer months for many types of offences. Seasonal fluctuation can somewhat be accounted for when interpreting crime trends by comparing the same time periods across time. For example, the results for the December 2023 quarter could be compared with the results for the December 2022 quarter. Other factors possibly contributing to changes in crime trends should also be considered when comparing different time periods.
   
• It is understood that not all offences come to the attention of the police, and some offences are less likely to be reported or detected than others. For example, elder abuse is less likely to be reported to the police than a stolen car. The reasons why some people do not report their experience of crime are very personal, but can relate to a lack of awareness that a crime has been committed, a fear of retaliation, a distrust of law enforcement, shame or embarrassment, and/or the type of relationship the victim has with the person committing the crime. 
  
  The underreporting of crime means that crime statistics based on information collected by the police provides an important indication of crime trends, rather than an absolute measure of crime occurring in the community. It can sometimes be difficult to understand if crime trend variations relate to actual changes in the amount of crime taking place, changes in reporting behaviour or changes in the way the criminal justice system responds to crime. In certain circumstances, an increase in offences traditionally associated with underreporting could be viewed to be a positive outcome, as it may mean that more people feel able to report their crime experience to the police.
   
• Since crime statistics provide an indication of crime trends, there is value in also referring to other sources of information when wanting to understand how much crime is taking place in the community. For example, the Australian Bureau of Statistics conducts surveys with community members (including those living in Queensland) about their views of personal safety and their experiences of crime. Various studies provide insight into levels and characteristics of illicit drug use taking place in the community. This includes the National Drug Strategy Household Survey conducted by the Australian Institute of Health and Welfare and the National Wastewater Drug Monitoring Program progressed by the Australian Criminal Intelligence Commission.
   
• Not all offences involve a person as the victim. For instance, if a young person breaches their bail for not meeting curfew requirements or a person is found to be in possession of illicit substances – an offence will be recorded, but no victim will be recorded. There are times when victim information may not be available for all types of offences, such as those associated with offences against property. These issues impact what can be counted when producing statistics on victims.
   

In other words, when describing crime and justice data and trends, care is required so that an accurate and balanced view is provided.