Suchergebnisse

"This paper proposes a model in which the decision maker builds an optimally simplified representation of the world which is "sparse," i.e., uses few parameters that are non-zero. Sparsity is formulated so as to lead to well-behaved, convex maximization problems. The agent's choice of a representation of the world features a quadratic proxy for the benefits of thinking and a linear formulation for the costs of thinking. The agent then picks the optimal action given his representation of the world. This model yields a tractable procedure, which embeds the traditional rational agent as a particular case, and can be used for analyzing classic economic questions under bounded rationality. For instance, the paper studies how boundedly rational agents select a consumption bundle while paying imperfect attention to prices, and how frictionless firms set prices optimally in response. This leads to a novel mechanism for price rigidity. The model is also used to examine boundedly rational intertemporal consumption problems and portfolio choice with imperfect understanding of returns"--National Bureau of Economic Research web site

"This paper incorporates a time-varying intensity of disasters in the Rietz-Barro hypothesis that risk premia result from the possibility of rare, large disasters. During a disaster, an asset's fundamental value falls by a time-varying amount. This in turn generates time-varying risk premia and thus volatile asset prices and return predictability. Using the recent technique of linearity-generating processes (Gabaix 2007), the model is tractable, and all prices are exactly solved in closed form. In the "variable rare disasters" framework, the following empirical regularities can be understood qualitatively: (i) equity premium puzzle (ii) risk-free rate-puzzle (iii) excess volatility puzzle (iv) predictability of aggregate stock market returns with price-dividend ratios (v) value premium (vi) often greater explanatory power of characteristics than covariances for asset returns (vii) upward sloping nominal yield curve (viiii) a steep yield curve predicts high bond excess returns and a fall in long term rates (ix) corporate bond spread puzzle (x) high price of deep out-of-the-money puts. I also provide a calibration in which those puzzles can be understood quantitatively as well. The fear of disaster can be interpreted literally, or can be viewed as a tractable way to model time-varying risk-aversion or investor sentiment"--National Bureau of Economic Research web site

This paper analyzes how bounded rationality affects monetary and fiscal policy via an empirically relevant enrichment of the New Keynesian model. It models agents' partial myopia toward distant atypical events using a new microfounded "cognitive discounting" parameter. Compared to the rational model, (i) there is no forward guidance puzzle; (ii) the Taylor principle changes: with passive monetary policy but enough myopia equilibria are determinate and economies stable; (iii) the zero lower bound is much less costly; (iv) price-level targeting is not optimal; (v) fiscal stimulus is effective; (vi) the model is " neo-Fisherian" in the long run, Keynesian in the short run. (JEL E12, E31, E43, E52, E62, E70)

A central difficulty in economics is to create a model with both good business cycle properties and asset pricing properties. I show how to solve this difficulty by a simple portable modeling device: the "disasterization" of models. Take an economy with good business cycle properties and create a new, "disasterized" economy, which is essentially identical to the original one except that disasters can destroy part of the capital stock and productivity. In such a disasterized economy, asset prices exhibit high and volatile risk premia, but macro variables remain unchanged. Perturbations of this benchmark allow for feedback from finance to macro.