Defence date: 25 September 2019Examining Board: Prof. Evi Pappa, Universidad Carlos III Madrid (Supervisor); Prof. Axelle Ferrière, Paris School of Economics; Prof. Guido Ascari, University of Oxford; Prof. Johannes Pfeifer, University of CologneThis thesis comprises three essays that analyze how uncertainty affects the macroeconomy. Each essay investigates a particular feature of uncertainty propagation. The first essay studies the effects of uncertainty shocks on economic activity, focusing on inflation. I consider standard New Keynesian models with Rotemberg-type and Calvo-type price rigidities. Despite the belief that the two schemes are equivalent, I show that they generate different dynamics in response to uncertainty shocks. In t...