COMPONENTS OF UNCERTAINTY
用机器学习方法区分不同类型的不确定性，发现其对宏观经济变量的影响因来源而异，存在好（扩张效应）和坏（收缩效应）两种不确定性。
Abstract Uncertainty is acknowledged to be a source of economic fluctuations. But, does the type of uncertainty matter for the economy's response to an uncertainty shock? This article offers a novel identification strategy to disentangle different types of uncertainty. It uses machine learning techniques to classify different types of news instead of specifying a set of keywords. The article finds that, depending on its source, the effects of uncertainty on a macroeconomic variable may differ. I find that both good (expansionary effect) and bad (contractionary effect) types of uncertainty exist.