For example, weather forecasting models are essentially predictive models in that no policy can be implemented to influence the weather in the very near future. Measures can, however, be taken as a result of the information provided by the forecasts; such as to evacuate a population which is likely to be exposed to a hurricane. In contrast, policy-oriented health expenditure forecasting models aim to inform policy makers about when and how to implement reforms and what effects those reforms are likely to produce.