This review article tries to answer four questions: (i) what are the stylized facts about uncertainty over time; (ii) why does uncertainty vary; (iii) do fluctuations in uncertainty matter; and (iv) did higher uncertainty worsen the Great Recession of 2007-2009? On the first question both macro...

Uncertainty varies strongly over time, rising by 50% to 100% in recessions and by up to 200% after major economic and political shocks. This paper shows that higher uncertainty reduces the responsiveness of R&D to changes in business conditions - a "caution-effect" - making it more persistent...

Macro data suggests a convex relationship between inflation and economic slack, but identifying causality is challenging. Using micro data from large panel surveys of UK and US firms we show that the response of prices to demand shocks is also convex at the firm level. We obtain similar results...

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...

Using firm-level panel data from the US Census Bureau and almost fifty other countries, we show that the skewness of the growth rates of employment, sales, and productivity is procyclical. In particular, during recessions, they display a large left tail of negative growth rates (and during...

We use survey data on an opt-in panel of around 2,500 US small businesses to assess the impact of COVID-19. We find a significant negative sales impact that peaked in Quarter 2 of 2020, with an average loss of 29% in sales. The large negative impact masks significant heterogeneity, with over 40%...