Comparisons - Crime and criminal justice

Comparisons

Comparing countries and years

Directly comparing crime figures between countries may not be relevant or valid, and may result in misleading inferences or wrong conclusions. This is because criminal justice systems, crime definitions, and crime statistics can vary a great deal between countries. Even if a crime figure changes from one year to the next, it does not always mean crime levels have actually changed.

Comparing crime figures between countries or years may be affected by differences or changes in:

  • legal systems and criminal justice systems
  • legislation, criminal law and legal definitions
  • the efficiency of police, prosecution, courts and prisons
  • recording practices (input/process/output)
  • recording, reporting and production systems
  • national crime definitions and international statistical definitions
  • statistical units and statistical populations
  • statistical definitions, reference times, counting methods and calculation methods
  • crime reporting rates

Remember to check the metadata from each country (information about definitions, etc.)

Comparing small figures

‘Small figures’ means:

  • low frequency (absolute number of crimes)
  • low rate (crimes per 100 000 people)
  • small proportion (e.g. % of women)
  • small change (from one year to the next).

Total figures from complete administrative records are considered precise and do not have sampling error like typical survey statistics. However, there may be other random errors in the data that can make small figures unreliable.

Some relative changes from one year to another may be big simply because the absolute figures are very small.