Experts measure crime statistics in three basic ways: from official reports, victim studies, and self-reporting data. Official statistics come from police departments at all levels and jurisdictions, and include regulatory agencies responsible for certain types of crimes, such as hunting or fishing violations. Crime statistics from victim studies routinely come from citizen questionnaires, private security companies, and social scientists who analyze criminal activity. Self-report statistics represent admissions from offenders to crimes that were previously unknown.
Official records used to compute crime statistics generally include police, corrections facilities, and court records. Law enforcement agencies keep data on different types of crime to gauge whether policing efforts are effective. They also apply the information to budget preparation and to determine training needs and staffing requirements. Crime statistics might reveal a need to reorganize a police department to focus more attention in areas where crime is increasing.
In some regions, crimes are never reported to law enforcement, especially if considered minor offenses. Government agencies typically survey citizens to measure the number and types of crimes that go unreported. The information provides more accurate crime statistics and might result in public awareness campaigns to encourage citizens to report offenses.
Annual reports of crime statistics are usually made available to the public for city-by-city comparison. The reports provide useful information, but may not give an exact indication of total crimes in an area due to population variations and bias on the part of the people reporting the data. The percentage of cases solved can also vary by city. In some communities, people might be more willing to cooperate with police by reporting crime and aiding law enforcement in solving them. Another factor that might skew crime statistics is pressure on police departments to report lower crime rates, which could lead to inaccurate reporting.
Analyzing court records might also prove difficult because various courts cover different jurisdictions and the way prosecutions are handled. Statistics may get skewed because several offenders could be arrested and prosecuted for a single crime, or a single criminal might be responsible for numerous offenses. Crimes statistics reported in one year might not correspond to prosecution data because it could take years before serious cases go to trial.
The accuracy of self-reporting and victim surveys can also vary. It may be difficult to verify an admission from an offender indicating he or she committed crimes that were never reported. Another glitch might occur when a victim reports a crime that stems from a civil problem the citizen believes is a criminal matter.
