We develop a set of necessary and sufficient conditions for equilibria to be determinate in a class of forward-looking Markov-switching rational expectations models, and we develop an algorithm to check these conditions in practice. We use three examples, based on the new Keynesian model of monetary policy, to illustrate our technique. Our work connects applied econometric models of Markov switching with forward-looking rational expectations models and allows an applied researcher to construct the likelihood function for models in this class over a parameter space that includes a determinate region and an indeterminate region.
JEL classification: E5
Key words: stability, nonlinearity, unique equilibrium, cross-regime indeterminacy, expectations formation, necessary and sufficient conditions
This paper is a thorough revision of the earlier draft titled "Understanding the New-Keynesian Model When Monetary Policy Switches Regimes" (NBER Working Paper no. 12965). The authors thank the referees and editors for thoughtful comments and Zheng Liu, Richard Rogerson, Eric Swanson, and John Williams for helpful discussions. They are grateful to Jacob Smith for excellent research assistance. This study is supported in part by National Science Foundation grant no. 0720839. The views expressed here are the authors' and not necessarily those of the Federal Reserve Bank of Atlanta or the Federal Reserve System. Any remaining errors are the authors' responsibility.
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