Defining the UCR Summary Reporting System and NIBRS
In the 1920s, the FBI began the Uniform Crime Reporting project as a collection of monthly crime counts from local law enforcement agencies, including collection of data via a mechanism known as the Summary Reporting System:
“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 Using NIBRS to study methodological sources of divergence between the UCR and NCVS categories, based on the most serious offense reported for each crime incident:
- murder and nonnegligent manslaughter
- rape
- robbery
- aggravated assault
- burglary
- larceny-theft
- motor vehicle theft
- arson
- 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 (“National Incident-Based Reporting System,” 2009).”
The SRS collection of arrest and offense data persisted even through the addition of further UCR datasets such as Law Enforcement Officers Killed and Assaulted (LEOKA) and the Hate Crime Statistics Program. After 60 years of collecting data via the SRS, the 1985 report Blueprint for the Future of the Uniform Crime Reporting Program by Poggio et al. (1985) examined the shortcomings in the way the SRS documented complex crime incidents, and it made suggestions for how these incidents could be more accurately measured. The collection of data under the NIBRS was started in response to these suggestions in 1989. “As opposed to the current summary reporting system, under unit-record reporting law enforcement agencies would report data on each offense and arrest individually… NIBRS collects data on up to 10 offenses per incident, and NIBRS collects data on types of offenses SRS does not count at all.” (“30 Questions and Answers About NIBRS Transition,” 2018).
Cook et al. (2021) explain why UCR SRS appears to “mask” more serious offenses under the “hierarchy rule”: “The SRS gathers data on a more limited set of offenses than is customary for most police agencies. For instance, it does not gather offense information about assault by intimidation, human trafficking, or kidnapping…The hierarchy rule ranks crimes in order of which is most severe and classifies a crime only according to the most severe offense. In effect, the SRS does not record all crimes that might have been committed in a single incident. In the event of a robbery where an aggravated assault also occurs, only the robbery would be recorded as an event.” In 2016, under recommendation from the Criminal Justice Information Services Advisory Policy Board, and with the approval of other major law enforcement organizations, the FBI director approved a plan “to transition all local, state, and tribal law enforcement agencies from SRS to NIBRS by January 1, 2021” and to transition the FBI to a “NIBRS-only crime data collection… Agencies that choose not to participate in NIBRS will not have their crime statistics included in the FBI’s nationwide crime statistics” (“30 Questions and Answers About NIBRS Transition,” 2018).
NIBRS and UCR SRS comparisons in the literature
Have the reasons used to justify transition to NIBRS been reflected in past research findings and scholarly engagement with the methodological issues of both the UCR and NIBRS? Some research comparing NIBRS data to the UCR SRS data has found that “gun violence is underestimated in the SRS compared to NIBRS” (Parker, 2022) and that NIBRS allows for the measurement of race/ethnicity-specific criminal incidents in a way that is not possible with UCR SRS (Fone et al., 2019). While Pattavina et al. (2017) acknowledge “the UCR captures a much greater frequency of arrests given its nearly complete coverage of the U.S. population,” they argue that differences between the datasets are negligible when the percentage share of offenses as total arrests is taken into account: “since UCR data only contain counts of reported crimes for index offenses, it is common to use the arrest data as a proxy for crime committed. The results reported here lend confidence to the use of NIBRS data as a highly representative sample of the total universe of arrests.”
When compared to the Supplementary Homicide Reports, Fegadel & Heide (2018) found consistency from NIBRS. They wrote, “Results indicated that the offender, victim, and weapons data for parents and stepfathers were generally very consistent across the two databases. Very few statistically significant differences between the two data sets were observed.” Compatibility when using NIBRS in tandem with National Crime Victimization Survey (NCVS) data to get a fuller picture of reported and unreported sexual assault has also been remarked upon in the literature, such as the ability to provide more detailed characteristics of both victims and offenders in an incident or the ability to examine and compare crime victimization rates reported or not reported to county police (Petraglia 2015; Addington 2006; Chilton & Jarvis 1999).
An FBI report from 2015 notes that the appearance of higher crime rates, due to differences between the SRS and NIBRS reporting standards, may be a concern among agencies transitioning to NIBRS. The report explained, “Agencies, of course, understand that NIBRS reporting does not actually increase crime, but often fear that the public, media, and government officials will misinterpret the apparent change in crime and attribute the increased crime counts to failed policing administration and leadership rather than a change in how the crime data are being reported.” That said, the report continues, “NIBRS participation increased from 663 reporting agencies in 1991 to 6,299 agencies in 2014” (Federal Bureau of Investigation, 2015). However, published analyses do not indicate a spike in apparent crime rates when comparing UCR SRS to NIBRS. For example, one article states, “UCR and NIBRS participation percentage was unrelated to difference frequency for all crime types…none of the independent variables specified in the methodology were related to difference percentage for any crime type with the exception of NIBRS participation percentage being associated with a modest reduction in difference percentage for aggravated assault” (Comer et al., 2021). The accuracy of NIBRS is more likely to come into question when compared to independent data collections, such as in Pattavina et al. (2013), where researchers found “more substance use in incidents of domestic violence than the NIBRS data reported” when compared to independent local police agency reports.
NIBRS and UCR Data at NACJD
What does this transition mean for datasets released under the UCR umbrella at NACJD? The National Archive of Criminal Justice Data (NACJD), located within ICPSR, currently has data available for NIBRS covering the years 1991 through 2020, and for UCR covering the years 1930 through 2018 available in multiple statistical software formats (SPSS, SAS, Stata, R, and ASCII) along with accompanying PDF codebooks. NACJD is in the process of curating more recent years of data for the rest of the UCR series as well as NIBRS, and the status of future datasets as impacted by the NIBRS transition is expected to be addressed by BJS in the near future. Immediate access to the master files for more recent years of data not available via NACJD can be obtained through the FBI’s Crime Data Explorer (CDE). Note that those master files are fixed-length, ASCII text format, compressed with WinZip software, and require some programming knowledge to extract the data.
Conclusion
This Research Spotlight does not reflect all of the existing research regarding UCR, NIBRS, or the transition from the UCR Summary Reporting System to NIBRS. Researchers should look for future updates from the Bureau of Justice Statistics regarding the most up-to-date status of the transition and its implications for future data releases. To see how each of the ICPSR studies mentioned in this Spotlight has been examined in other scholarly literature, to gain ideas for extending prior research, or to conduct a larger literature review, you can search the ICPSR Bibliography of Data-related Literature using query terms such as “uniform crime reporting” or “national incident based reporting.” Users can also access related publications for a particular NIBRS or UCR study by clicking on the “Data-related Publications” tab from the ICPSR and NACJD study home pages.
When authoring publications that include your secondary analysis of study data downloaded from ICPSR, be sure to cite the study in the publication’s references section, using the provided data citation and unique identifier (in the form of a URL containing a DOI). Once your paper is published, submit its citation to the ICPSR Bibliography via this form, so it can be added to ICPSR’s collection of linked data-related literature, enabling others to find, learn from, and cite your work.
