How Robust is Robust Control in Discrete Time?

By applying robust control, the decision maker wants to make good decisions when his model is only a good approximation of the true one. Such decisions are said to be robust to model misspecification. In this paper it is shown that, in many situations relevant in economics, a decision maker applying robust control implicitly assumes that today’s worst-case adverse shock is serially uncorrelated with tomorrow’s worst-case adverse shock. Then, further investigation is needed to see how strong is the ‘immunization against uncertainty’ provided by these popular frameworks.