TY  - JOUR
AU  - Gabaix,Xavier
TI  - A Sparsity-Based Model of Bounded Rationality
JF  - National Bureau of Economic Research Working Paper Series
VL  - No. 16911
PY  - 2011
Y2  - March 2011
UR  - http://www.nber.org/papers/w16911
L1  - http://www.nber.org/papers/w16911.pdf
N1  - Author contact info:
Xavier Gabaix
New York University
Finance Department
Stern School of Business
44 West 4th Street, 9th floor
New York, NY 10012
Tel: 212-998-0257
Fax: 212-995-4233
E-Mail: xgabaix@stern.nyu.edu
AB  - 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.
ER  -