International Macroeconomic Policy Coordination When Policy-Makers Disa gree on the Model

The existing literature on international macroeconomic policy coordination makes the unrealistic assumption that policy-makers all know the true model, from which it follows in general that the Nash bargaining solution is superior to the Nash non-cooperative solution. But everything changes once we recognize that policy-makers' models differ from each other and therefore from the "true" model. It is still true that the two countries will in general be able to agree on a cooperative policy package that each believes will improve the objective function relative to the Nash non-cooperative solution. However, the bargaining solution is as likely to move the target variables in the wrong direction as in the right direction, in the light of a third true model. This paper illustrates these theoretical points with monetary and fiscal multipliers taken from simulations of eight leading international econometric models. (It is a sequel to NBER Working Paper 1925, which considered coordination between the domestic monetary and fiscal authorities.) Here we first consider coordination between U.S. and non-U.S. central banks. We find that out of 512 possible combinations of models that could rep