Data - Crime and criminal justice
INformation on data
Comparing countries and years
Direct comparison of crime figures between countries may not be relevant or valid, and result in misleading inferences or wrong conclusions.
The reason is that the 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.
Comparison of crime figures between countries may be affected by different:
- Legal system and criminal justice system;
- Legislation, criminal law and legal definitions;
- Efficiency of police, prosecution, courts and prisons;
- Recording practice (input/process/output);
- Recording, reporting and production system;
- National crime definitions and international statistical definitions;
- Statistical unit and statistical population;
- Statistical definitions, reference times, counting methods and calculation methods;
- Crime reporting rates.
Comparing small figures
"Small figure" refers to:
- low frequency (absolute number of crimes);
- low rate (crimes per 100,000 people);
- small proportion (for instance % of women); or
- 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.