The FBI’s UCR Program is a nationwide, cooperative statistical effort of more than 17,000 city, university and college, county, state, tribal, and federal law enforcement agencies voluntarily reporting data on crimes brought to their attention. The Violent Crime Index includes the following offenses: Murder and non-negligent manslaughter, forcible rape, robbery, and aggravated assault. These are Part I offenses and are serious crimes by nature and/or volume.
The UCR Program uses the following method to estimate crime in the case of missing reports at the Metropolitan Statistical Area, state, and national levels. For agencies that did not report data, the UCR Program staff assign the same percental crime volumes based on the crime statistics of similar areas within a state. The UCR Program staff consider the size of an agency, type of jurisdiction, and geographic location in the estimation process. The UCR Program staff use a similar procedure for estimating the number of arrests for the Nation.