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An official website of the United States government, Department of Justice.

Survey Methodologies

Survey of Prison Inmates (SPI)

The Survey of Prison Inmates (SPI) is a periodic, cross-sectional survey of the state and sentenced federal prison populations. Its primary objective is to produce national estimates for the state and sentenced federal prison populations across a variety of domains, including but not limited to demographic characteristics, current offense and sentence, incident characteristics, firearm possession and sources, criminal history, socioeconomic characteristics, family background, drug and...