Methodologies Explain Potential Differences in UCR Data
The Uniform Crime Reporting (UCR) Program is in the process of migrating its data releases from static 
web publications hosted on www.fbi.gov to more dynamic, multi-year displays of data on the Crime 
Data Explorer (CDE).  Just as the data in the tables of the annual publications sometimes differ from 
those available in the master files for the same year, the data in the publication tables may also differ 
from those released on the Explorer Pages of the CDE.  These variations are due to the difference in 
methodologies between the publication tables and data displayed on the CDE.

Historically, the agency, state, regional, and national data in Crime in the United States, Hate Crime 
Statistics, and Law Enforcement Officers Killed and Assaulted must pass internal data quality reviews 
prior to publication. According to the methodology, data that do not meet established criteria are not 
included in the publication tables.  Individuals who typically use data from tables in Crime in the United 
States and other UCR web publications on www.fbi.gov will continue to have access to that format via 
the downloadable publication tables for 2020 and prior years. 
 
As is the case with all the data files released for 1960 through 2020, the data displayed on the CDE 
include all reported data from agencies and entities aggregated from the agency data, such as states.   
According to methodology of typical open data websites, all reported data remain in file.  Individuals 
who typically work with data files, such as the Master Files, can also access the CDE releases of data 
from 2020 and earlier for data based on the same quality methodology.

Starting with the release of 2021 data in calendar year 2022, the UCR Program will be consolidating its 
data quality review and management practices, which will reduce or eliminate potential differences 
between the two presentations going forward.  

Files last modified:  March 15, 2021
