Background on the collection of reported crime data
Since 1930, the Federal Bureau of Investigation's Uniform Crime Reporting (UCR) Program has collected information about crimes known to and arrests made by law enforcement. The UCR Summary Reporting System (SRS) collected monthly counts of the number of crimes known to law enforcement from thousands of agencies throughout the United States. Information on the number of crimes known was recorded for ten offense categories, based on the most serious offense reported for each crime incident:
- murder and nonnegligent manslaughter
- aggravated assault
- motor vehicle theft
- human trafficking - commercial sex acts
- human trafficking - involuntary servitude
In addition, the SRS collected counts of arrests only for an additional set of offense categories, broken down by the age, sex, and race of the arrestee.
Building a new vision for crime statistics
In 1982, BJS and the FBI sponsored a study of the UCR Program, with the objective of revising the program to meet the changing needs of law enforcement moving into the 21st century. This effort to provide more comprehensive and detailed crime statistics resulted in the report Blueprint for the Future of the Uniform Crime Reporting Program, which proposed the development and implementation of a new data collection, the National Incident-Based Reporting System (NIBRS).
Offenses and Data Elements Measured in the NIBRS
The NIBRS expands on the ten offense types measured in the SRS and collects incident and arrest information from law enforcement agencies for 22 categories of offenses in Group A, as well as arrest information only for ten additional offenses in Group B.1
In addition to counts of crimes and arrests, NIBRS was designed to collect detailed information on the attributes of each crime incident known to law enforcement, including—
- the date, time, and location of the incident
- a detailed list of all offenses that occurred in the incident, not just the most serious offense
- demographic information on each victim and offender involved in the incident
- the relationships between each of the victims and the offenders
- other details of the incident, including victim injury, type of weapon involved, alcohol or drug involvement, property loss, and drugs seized
- clearance information, including both arrest and clearances by exceptional means
- date of arrest and arrestee demographics.
Law enforcement agencies have been gradually moving from reporting summary statistics to the FBI to reporting to NIBRS, a shift that is reflective of a larger trend among police agencies toward collecting more detailed, incident-based case information. In the most recent Crime in the United States report, the FBI stated that for 2012 a total of 6,115 law enforcement agencies reported their UCR crime statistics via NIBRS,2 out of 18,290 total police agencies participating in the UCR program. In 2012 NIBRS-contributing agencies served approximately 30% of the U.S. population3 and accounted for 28% of all crime reported to the UCR Program. While the number of law enforcement agencies reporting NIBRS data to the FBI continues to grow, many of the police departments representing large metropolitan areas throughout the nation still do not contribute data to the system. As a result, at the national level, incident-based law enforcement data are still unable to address the current information needs of policymakers, researchers, the media, and the public.
To spur the development of NIBRS into a nationally representative source of detailed crime statistics, in 2012 BJS spearheaded an initiative titled the National Crime Statistics Exchange (NCS-X). NCS-X is designed to generate nationally representative, incident-based data on crimes reported to law enforcement agencies by recruiting a select sample of agencies to report NIBRS data to the FBI. In 2013, BJS and the FBI signed a joint statement of support for NCS-X and agreed to work together to expand NIBRS coverage through funding, training, and technical assistance to law enforcement agencies across the United States.
2 NIBRS 2012, NIBRS Participation by State.
3 Among the U.S. population covered by UCR participants. For more information, see About Crime in the United States, 2012 on the FBI website (retrieved January 14, 2014).