Growth Expectations, Undue Optimism, and Short-Run Fluctuations
提出两步法识别信念冲击（对当前经济状态的预期冲击），利用专业预测者调查的同期预测误差，发现信念冲击解释了约三分之一短期产出波动，并引发宏观经济变量的联动调整。
Abstract This paper proposes a two-step procedure in order to identify belief shocks—shocks to expectations about the current state of the economy. First, we use the Survey of Professional Forecasters to measure nowcast errors about contemporaneous output growth. Second, we extract belief shocks from nowcast errors, once by regressing them on existing measures of structural shocks and once by imposing sign restrictions on a VAR model. Using both approaches, we find that belief shocks trigger similar adjustment dynamics and a high degree of co-movement across macroeconomic variables. Belief shocks account for about onethird of short-run output fluctuations.