Samenvatting

Forecasting systems require large quantities of data as input for reliable and adequate estimates. These estimates are used by policy makers to develop and implement effective and sound planning policies. In this case study, a forecasting system is presented to estimate the capacity needed in the near future in the Dutch justice field that has been in use already for more than ten years. Based on thousands of regression equations describing the behaviour and interaction of some 1500 variables, both inside and outside the justice field, it is performing better than other methods like simple extrapolations. The forecasts, on which the effects of future policy measures are added as well, are used for the budgeting of the Ministry of Justice. Besides, an example is given of a scenario study - a what/if analysis - where the forecasting system is used to look into the effects on the prison capacity needed if either the number of crimes or the way the criminal justice system reacts on crimes changes.