Identification via heteroskedasticity exploits differences in variances across regimes to identify parameters in simultaneous equations. I study weak identification in such models, which arises when variances change very little or the variances of multiple shocks change close to proportionally....

This paper explores Knightian model uncertainty about dynamic misspecification as a possible explanation of the considerable difference between estimated interest rate rules and optimal feedback descriptions of monetary policy. In the literature on robust control, Knightian uncertainty about a...