| Abstract: | We study how decision-makers' concerns about robustness affectprices and quantities in a stochastic growth model. In the modeleconomy, growth rates in technology are altered by infrequentlarge shocks and continuous small shocks. An investor observesmovements in the technology level but cannot perfectly distinguishtheir sources. Instead the investor solves a signal extractionproblem. We depart from most of the macroeconomics and financeliterature by presuming that the investor treats the specificationof technology evolution as an approximation. To promote a decisionrule that is robust to model misspecification, an investor actsas if a malevolent player threatens to perturb the actual data-generatingprocess relative to his approximating model. We study how aconcern about robustness alters asset prices. We show that thedynamic evolution of the risk-return trade-off is dominatedby movements in the growth-state probabilities and that theevolution of the dividend-price ratio is driven primarily bythe capital-technology ratio. |
