The NPS and NCRP are flagship data collections for BJS that measure the size and nature of state and federal prison populations on an annual basis. The two collections complement each other by obtaining aggregate and detailed individual-level information on prisoners for use in characterizing the prison population over time, as well use in statistical analyses that have policy implications. The NPS collects aggregate counts of the male and female custody and jurisdictional prison populations on December 31st of each year. State departments of corrections (DOCs) and the Federal Bureau of Prisons (BOP) use their administrative records to tally their prison populations by the physical location where inmates are held, types of prison admissions and releases during the past year, race/ethnicity, and capacity of the facilities to hold prisoners in their custody. NPS also provides annual information on the number of confirmed cases of HIV/AIDS and current testing policies for these conditions.
Through the NCRP, BJS collects individual (or offender) level data on prisoners entering or leaving the custody of state prison systems and post-custody community supervision programs (PCCS; formerly known as the NCRP data, collected annually since 1983, are derived from state prison and PCCS administrative records, and currently consist of five separate files for each year: prison admissions, census of state prisoners on December 31, prison releases, entry to PCCS programs, exits to PCCS programs. A major improvement in NCRP data in the past five years has been to link the prison and PCCS records into for the majority of states submitting data. BJS uses these data to study a wide variety of special topic issues in corrections such as recidivism of state prisoners (by linking the NCRP data to criminal history records), prisoner reentry, aging of the prison population, trends in state parole, outcomes of parole supervision, and other issues. Additionally, BJS uses these data to support its ongoing efforts to study changes in racial and offense composition of national corrections populations, movements and transitions between stages of the corrections process, and to compare differences among states correctional populations.