Scottish prison population projections: September 2024

6 Conclusions

As of 31^st July 2024, the prison population was around 7,950. The modelling indicates a projected range for the average daily total prison population of between 7,750 to 9,250 in January 2025. The population has been growing rapidly since ER was implemented but it is unclear whether this will continue, hence the need for the modelling to account for this possibility (as well as potential reversal) in the months ahead.

The rapid rise in the prison population since ER in June/July 2024, comes at a time when the population was already relatively high following substantial growth in 2023/2024. In the first publication of June 2023, only low, central and high court throughput scenarios were reported. Since the November 2023 publication^[40], six additional scenarios have been included which tend to help ensure the projections account for periods of high inflow to the population (whether into the remand or sentenced population). Over the course of the next few months remand arrivals, sentenced arrivals and case conclusion levels will be monitored to assess with which scenarios the actual prison population numbers are most closely aligned.

For several reasons, modelling the future prison population using the microsimulation becomes less accurate the further ahead it is projected (whether due to systematic errors in the model, inaccurate assumptions due to unforeseen circumstances, or due to changed circumstances that the model is not built to account for). Experience to date suggests that a maximum projection period of six months allows for reliable projections.

As previously highlighted, the key factors impacting changes in the prison population in the short term will be the flows into and out of the remand and sentenced populations. This is influenced by the court recovery programme, for example the resource re-allocation from summary to solemn which took place in April 2023. It is assumed in the projections that the number of court rooms allocated to summary and solemn procedure will be unchanged until at least January 2025. SCTS reporting has indicated that elevated levels of summary demand in 2023 meant that the level of outstanding summary trials has levelled off rather than continuing to fall^[41].