@techreport{NBERw12948,
 title = "Beliefs, Doubts and Learning: Valuing Economic Risk",
 author = "Lars Peter Hansen",
 institution = "National Bureau of Economic Research",
 type = "Working Paper",
 series = "Working Paper Series",
 number = "12948",
 year = "2007",
 month = "March",
 URL = "http://www.nber.org/papers/w12948",
}