Scottish Prison Population Projections: June 2024 Edition

This report presents short-term Scottish prison population projections for the six month period from May to October 2024. They have been produced using ‘microsimulation’ scenario modelling which simulates prison arrivals and departures, and estimates the number of individuals in prison.

6 Conclusions

As of 30th April 2024, the prison population was around 8,250. The modelling indicates a projected range for the average daily total prison population of between 7,650 to 9,150 in October 2024. The decision to include data from April 2024 in the modelling assumptions means the projected population range to October 2024 includes the levels which might be reached if population inflows continue at the high levels observed in recent months. It is unclear at this stage, whether the rate of population increase will remain elevated, 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 in recent months, comes at a time when the population was already relatively high following a period of substantial growth in 2023. As a result of increasing pressures on prison estate capacity, the Scottish Government recently announced a number of actions it intends to take to address and mitigate the rising prison population[33],[34]. It should be noted that these latest prison population projections do not include the effects of any measures announced by the Scottish Government, as they have yet to be considered and/or approved by the Parliament.

In the first publication of June 2023, only low, central and high court throughput scenarios were reported. Since the November 2023 publication, six additional scenarios have been included[35], which feature varying remand arrivals (low, central and high) combined with court throughput variations (also low, central and high). 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 October 2024. 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[36].



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