美联储具有不确定私营部门前景的最优货币政策

Optimal Monetary Policy with Uncertain Private Sector Foresight

Introduction

Monetary policy operates in an environment of significant uncertainty due to the private sector's limited foresight in forming expectations. This paper contributes to the literature by studying optimal time-consistent monetary policy when policymakers are uncertain about the nature of expectations formation. The model used is the New Keynesian, finite horizon planning (NK-FHP) framework, which assumes that households and firms have limited foresight, making long-term planning difficult.

Key Features of the NK-FHP Model

• Finite Horizon Planning: Households and firms can only accurately predict the economy's evolution up to a finite horizon, relying on structural relationships to evaluate potential paths.
• Microfoundations for Inflation Scares: The model provides a foundation for "inflation scares," where long-term inflation expectations can persistently diverge from a central bank's inflation target.

Optimal Time-Consistent Policy Under Uncertainty

• Risk Management Considerations: The presence of uncertainty about the planning horizons of agents introduces a risk of inflation scares. This leads to a need for preemptive measures to avoid such scares.
• Lean Against the Wind Principle: In the NK-FHP model, optimal policy often involves a "leaning against the wind" approach, where policy contracts aggregate demand when inflation is above target. However, this principle needs to be adjusted for short-term planning horizons.
• Preemptive Motive: Policymakers must anticipate and act preemptively to prevent inflation scares. This involves adjusting policy based on the risk of future inflation pressures.

Empirical Relevance

• Model Fit: The NK-FHP framework has been shown to fit macroeconomic data better than other behavioral models, including those with rational expectations and exogenous price indexation.
• Parameter Estimates: Parameter estimates from the model help quantify the importance of limited and uncertain foresight in conducting monetary policy.

Conclusion

When households and firms have long planning horizons, optimal policy aligns with the "leaning against the wind" strategy. However, when planning horizons are short, policymakers must account for the risk of inflation scares and adjust their strategies accordingly. The model highlights the need for proactive measures to ensure inflation remains close to target, thereby anchoring private sector beliefs about future inflation.

This analysis underscores the importance of considering the limited foresight of economic agents in designing optimal monetary policy, especially during periods of uncertainty.