Crime data is collected from law enforcement agencies and victim surveys. Statistics are generated from the data to measure the risk and amount of crime within a population. Crime rate is one method of measuring crime.
In 1929, the International Association of Chiefs of Police created the Uniform Crime Reporting (UCR) Program, the first effort to generate reliable crime statistics. To supplement the UCR data and generate more accurate information, the National Crime Victimization Survey (NCVS) was conducted for the first time in 1966. Data from both collection methods are used in calculating crime rates.
Approximately 17,000 law enforcement agencies submit data to the FBI for the UCR Program. Since not all crimes are reported to the police, the NCVS is conducted by the Census Bureau to obtain crime information directly from victims regardless of when and if they reported the crime.
Crime rate is calculated by dividing the actual number of crime occurrences by the total population; this is also considered the number of times a crime could have occurred. To change the scale unit, multiply the per capita rate by the desired unit of measure. The Bureau of Justice Statistics typically reports crime rates as per 1,000 persons.
Crime rates are used by government agencies and officials to make policy decisions and to determine funding for programs. The FBI uses the information to make decisions in law enforcement management, operations and administration.
Law enforcement agencies may fail to report to UCR Program because of computer problems, a change in their record-keeping system or a shortage of staff to maintain the records. In the NCVS, victims may give inaccurate accounts.