Demographically disaggregated projections of prison populations

Abstract

The need for improved long-run projections of prison populations has increased in recent years because of record-high numbers of inmates and severe overcrowding in state and federal prisons, and because of the growing importance of changing demographic factors in influencing corrections populations. A model is developed for projecting: general population demographics; demographic- and offense-specific arrest rates, imprisonment probabilities, and times served; and then the size and composition of prison populations. Model parameters are estimated for Pennsylvania and are shown to be sensitive to demographic factors, particularly age and race. Projections of future arrests, prison commitments, and prison population are developed for Pennsylvania using projections of demographic changes in the state's population. Arrests are expected to peak in 1980, prison commitments are expected to peak in 1985, and prison populations are expected to peak in 1990, with the subsequent declines reflecting the maturation of the postwar baby boom children out of the highly crime-prone ages and, somewhat later, out of the highly prison-prone ages.