We explore the business cycle implications of expectation shocks and of two well-known psychological biases, optimism and overconfidence. The expectations of optimistic agents are biased toward good outcomes, while overconfident agents overestimate the precision of the signals that they receive....

We propose uncertainty shocks as a new shock that drives business cycles. First, we demonstrate that microeconomic uncertainty is robustly countercyclical, rising sharply during recessions, particularly during the Great Recession of 2007-2009. Second, we quantify the impact of time-varying...

Heterogeneous firm models are ubiquitous in modern macroeconomics. We revisit a central feature of these models: the idiosyncratic shock process faced by firms. Using a large representative firm-level dataset, we document nonparametrically that the common assumption, a Gaussian AR(1) shock...