Finance and Economics Discussion Series (FEDS)
June 2000
On Signal Extraction and Non-Certainty-Equivalence in Optimal Monetary Policy Rules
Eric T. Swanson
Abstract:
A standard result in the literature on monetary policy rules is that of certainty equivalence: given the expected values of all the state variables of the economy, policy should be set in a way that is independent of all higher moments of those variables. Some exceptions to this rule have been pointed out by Smets (1998), who restricts policy to respond to only a limited subset of state variables, and by Orphanides (1998), who restricts policy to respond to estimates of the state variables that are biased. In contrast, this paper studies unrestricted, fully optimal policy rules with optimal estimation of state variables. The rules in this framework exhibit certainty equivalence with respect to estimates of an unobserved, possibly complicated, state of the economy X, but are not certainty-equivalent when 1) a signal-extraction problem is involved in the estimation of X, and 2) the optimal rule is expressed as a reduced form that combines policymakers' estimation and policy-setting stages. In general, I show that it is optimal for policymakers to attenuate their reaction coefficient on a variable about which uncertainty has increased, while responding more aggressively to all other variables, about which uncertainty hasn't changed.
Full paper (325 KB Postscript)Keywords: Signal extraction, certainty equivalence, monetary policy rules, Taylor rule
PDF: Full Paper
Disclaimer: The economic research that is linked from this page represents the views of the authors and does not indicate concurrence either by other members of the Board's staff or by the Board of Governors. The economic research and their conclusions are often preliminary and are circulated to stimulate discussion and critical comment. The Board values having a staff that conducts research on a wide range of economic topics and that explores a diverse array of perspectives on those topics. The resulting conversations in academia, the economic policy community, and the broader public are important to sharpening our collective thinking.