The NIBRS is based on the collection of data from the records management systems of federal, state and local law enforcement agencies. The incidents and arrests that are included into the national database are categorized into groups based on the severity of the crime. The two offence groups are:
- Group A – consisting of 46 particular crimes in 22 offence categories, these are usually felonies or misdemeanors of a violent or antisocial nature.
- Group B – consisting of 11 specific offences, mainly of nonviolent nature.
The FBI curates the NIBRS data submitted by the state and local law enforcement agencies and the agencies participating have to adhere to a set standard. The data is submitted in a set format and has nine segments or categories of data that is reported on.