On optimal control and macroeconomic policy

Control theory has important contributions to make to the theory of macro-economic policy. These include a unified view of estimation, forecasting and control and a consequently clearer focus in identifying performance criteria. Further, the methods of control theory imply objectivity and a need for assumptions to be made explicit. By contrast, the UK lacks a research body for forecasting and policy evaluation detached from doctrinal or methodological commitment. Engineering control methods, however, diverge from those wholly acceptable to economic systems in that, in the latter, the controller is himself part of the system he controls and some of his controls operate only indirectly. A further difference is that economics cannot as yet furnish the controller with reliable models of system behaviour linking policy instruments to set targets.