A distinguishing feature of macro stress testing exercises is the use of macroeconomic models in scenario design and implementation. It is widely agreed that scenarios should be based on "rare but plausible" events that have either resulted in vulnerabilities in the past or could do so in the future.
Historical narratives typically associate financial crises with credit expansions and asset price misalignments. The question is whether some combination of measures of credit and asset prices can be used to predict these events.
Changes in risk perception have been used in various contexts to explain shorter-term developments in financial markets, as part of a mechanism that amplifies fluctuations in financial markets, as well as in accounts of "irrational exuberance."
Explanations of changes in asset prices as being due to exogenous changes in risk appetite, although arguably controversial, have been popular in the financial community and have also received some attention in attempts to account for recent financial crises. Operational versions of these explanations are based on the assumption that changes in asset prices can be decomposed into a part that can be attributed to changes in riskiness and a part attributable to changes in risk aversion, and that some quantitative measure can capture these effects in isolation.
In a recent attempt to account for the equity-premium puzzle within a representative-agent model, Cecchetti, Lam, and Mark (2000) relax the assumption of rational expectations and in its place use the assumption of distorted beliefs. The author shows that the explanatory power of the distorted beliefs model is due to an inconsistency in the model and that an attempt to remove this inconsistency removes the model's explanatory power.
