Scottish prison population projections: October 2025
This report presents short-term Scottish prison population projections for the six month period from October 2025 to March 2026.
Background
The ‘microsimulation’ scenario modelling approach simulates the arrivals and departures of individuals to and from the prison population to estimate the number of individuals in prison on a given future date. The model uses individual-level data to construct a representation of the population of interest. Using known probabilities, the model can simulate changes in individuals’ custody status over time. The first issue of the Scottish prison population projections[1] provided a detailed overview of the modelling technique used.
Data and assumptions
To produce outputs, the model draws on selected court activity data, for example, court hearing volumes at various stages (such as pre-trial or trial) in High Court, Sheriff Court Summary, and Sheriff Court Solemn. This data is used to estimate levels of remand arrivals in the coming months. The model also incorporates assumptions on future court capacities, which are among the most important factors influencing short- and medium-term changes in the prison population.
Modelling limitations
As the model can be validated against historical data and can reflect a wide variety of dynamics, it is suitable for forecasting in the short- and medium-term. However, due to ongoing uncertainty in the justice system’s recovery (e.g., the rate at which court backlogs can be reduced by the recovery programme), which affects the model’s assumptions and limits its longer-term predictive power, currently only a six-month projection is generated using the model.
The model does not currently simulate flows by crime type, so trends specific to different crime categories are not explicitly modelled.
Report structure
The rest of this report is organised as follows:
- Section 3 provides a brief overview of the prison population from 2020 to 2025 and trends in court demand from 2014 to 2025. It also discusses the drivers of population growth since 2023.
- Section 4 outlines the assumptions and scenarios used to project the prison population and explains how previous projections are validated against actual population data to assess robustness.
- Section 5 presents the latest population projection results for the period from October 2025 to March 2026.
- Section 6 summarises the key conclusions from the modelling and discusses the short-term factors that may influence prison population levels.
- Section 7 provides a technical annex, covers some technical aspects of the modelling approach and how the scenario variant assumptions are derived.
[1] For more information, refer to Scottish prison population projections - gov.scot (www.gov.scot), 1st June 2023.