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Working Paper
Doubts about the Model and Optimal Policy
This paper analyzes optimal policy in setups where both the leader and the follower have doubts about the probability model of uncertainty. I illustrate the methodology in two environments: a) an industry populated with a large firm and many small firms in a competitive fringe, where both types of firms doubt the probability model of demand shocks, and b) a general equilibrium economy, where a policymaker taxes linearly the labor income of a representative household in order to finance an exogenous stream of stochastic spending shocks. The policymaker can distrust the probability model of ...
Working Paper
Ambiguity Aversion and Variance Premium
This paper offers an ambiguity-based interpretation of variance premium?the difference between risk-neutral and objective expectations of market return variance?as a compounding effect of both belief distortion and variance differential regarding the uncertain economic regimes. Our approach endogenously generates variance premium without imposing exogenous stochastic volatility or jumps in consumption process. Such a framework can reasonably match the mean variance premium as well as the mean equity premium, equity volatility, and the mean risk-free rate in the data. We find that about 96 ...
Working Paper
Fiscal Austerity in Ambiguous Times
This paper analyzes optimal fiscal policy with ambiguity aversion and endogenous government spending. We show that, without ambiguity, optimal surplus-to-output ratios are acyclical and that there is no rationale for either reduction or further accumulation of public debt. In contrast, ambiguity about the cycle can generate optimally policies that resemble "austerity" measures. Optimal policy prescribes higher taxes in adverse times and front-loaded fiscal consolidations that lead to a balanced primary budget in the long-run. This is the case when interest rates are sufficiently responsive ...
Working Paper
Ambiguity in Securitization Markets
During the financial crisis of 2008, origination and trading in asset-backed securities markets dropped dramatically. I present a model with ambiguity averse investors to explain how such a market freeze could occur and to investigate how ambiguity affects origination and securitization decisions. The model captures many features of the crisis, including market freezes and fire sales, as well as the timing and duration of the freeze. The presence of ambiguity also reduces real economic activity. Lastly, I consider the differing implications of ambiguity and risk, as well as the role of ...
Discussion Paper
Model Uncertainty and Policy Design
This article illustrates the main challenges and forces that emerge in optimal policy design when there are doubts about the probability model of uncertainty. Model doubts can stem from either the side of the public or the side of the policymaker, and they can give rise to cautious probabilistic assessments. A basic idea that surfaces in setups with model uncertainty is the management of the public's pessimistic expectations by the policymaker. The article also presents several implications of this idea.
Journal Article
Model Uncertainty and Policy Design
This article illustrates the main challenges and forces that emerge in optimal policy design when there are doubts about the probability model of uncertainty. Model doubts can stem from either the side of the public or the side of the policymaker, and they can give rise to cautious probabilistic assessments. A basic idea that surfaces in setups with model uncertainty is the management of the public's pessimistic expectations by the policymaker. The article also presents several implications of this idea.