Such models can help to direct efforts to where they may be the most effective. Emerging onto the scene are approaches that enable detailed “what if” questions about the introduction of polices related to prevention, treatment, organisation and financing of care, technological innovation and health-sector productivity. Further, there are new' approaches that enable health expenditures to be situated in a broader context: they can take account of factors such as the health, longevity, and productivity of the population, and investment, consumption and economic growth which can help policy makers evaluate “value for money”. In the system, a forecast from one model can provide a needed input parameter for another model.