Search Results
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
A Robust Capital Asset Pricing Model
We build a market equilibrium theory of asset prices under Knightian uncertainty. Adopting the mean-variance decisionmaking model of Maccheroni, Marinacci, and Ruffino (2013a), we derive explicit demands for assets and formulate a robust version of the two-fund separation theorem. Upon market clearing, all investors hold ambiguous assets in the same relative proportions as the assets' market values. The resulting uncertainty-return tradeoff is a robust security market line in which the ambiguous return on an asset is measured by its beta (systematic ambiguity). A simple example on portfolio ...
Discussion Paper
Combining Models for Forecasting and Policy Analysis
Model uncertainty is pervasive. Economists, bloggers, policymakers all have different views of how the world works and what economic policies would make it better. These views are, like it or not, models. Some people spell them out in their entirety, equations and all. Others refuse to use the word altogether, possibly out of fear of being falsified. No model is “right,” of course, but some models are worse than others, and we can have an idea of which is which by comparing their predictions with what actually happened. If you are open-minded, you may actually want to combine models in ...
Working Paper
Optimal monetary policy under model uncertainty without commitment
This paper studies the design of optimal time-consistent monetary policy in an economy where the planner trusts its own model, while a representative household uses a set of alternative probability distributions governing the evolution of the exogenous state of the economy. In such environments, unlike in the original studies of time-consistent monetary policy, managing households' expectations becomes an active channel of optimal policymaking per se, a feature that the paternalistic government seeks to exploit. We adapt recursive methods in the spirit of Abreu, Pearce, and Stacchetti (1990) ...
Discussion Paper
Choosing the Right Policy in Real Time (Why That’s Not Easy)
As an economist, you make policy recommendations at any point in time that depend on what model of the economy you have in mind and on your assessment of the state of the economy. One can see these points play out in the current discussion about the timing of interest rate liftoff and the speed of the subsequent renormalization. If you think nominal rigidities are not all that important, you are likely to conclude that accommodative policies won’t do much for growth but will generate inflation. Similarly, if you are convinced that the economy is already firing on all cylinders, you may see ...
Working Paper
On Monetary Policy, Model Uncertainty, and Credibility
This paper studies the design of optimal time-consistent monetary policy in an economy where the planner and a representative household are faced with model uncertainty: While they are able to construct and agree on a reference model (probability distribution) governing the evolution of the exogenous state of the economy, a representative household has fragile beliefs and is averse to model uncertainty. In such environments, management of households' expectations becomes an active channel of optimal policymaking per se. A central banker who respects the fact that private sector models are ...
Report
Real-time inflation forecasting in a changing world
This paper revisits the accuracy of inflation forecasting using activity and expectations variables. We apply Bayesian-model averaging across different regression specifications selected from a set of potential predictors that includes lagged values of inflation, a host of real activity data, term structure data, nominal data, and surveys. In this model average, we can entertain different channels of structural instability by incorporating stochastic breaks in the regression parameters of each individual specification within this average, allowing for breaks in the error variance of the ...
Working Paper
Growth and Welfare Gains from Financial Integration Under Model Uncertainty
We build a robustness (RB) version of the Obstfeld (1994) model to study the effects of financial integration on growth and welfare. Our model can account for the empirically observed heterogeneity in the relationship between growth and volatility for different countries. The calibrated model shows that financial integration leads to significantly larger gains in growth and welfare for advanced countries than developing countries, with some developing countries experiencing growth and welfare loss in financial integration. Our analytical solutions help uncover the key mechanisms by which this ...
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.
Discussion Paper
No Good Deals—No Bad Models
The recent financial crisis has highlighted the significance of unhedgable, illiquid positions in complex securities for individual financial institutions and for the global financial system as a whole. Indeed, the Basel Committee on Banking Supervision notes that "One of the key lessons of the crisis has been the need to strengthen the risk coverage of the capital framework. Failure to capture major on- and off-balance sheet risks, as well as derivative related exposures, was a key destabilizing factor during the crisis."