The bilateral trade effects of announcement shocks: Brexit as a natural field experiment
利用合成控制法分析2016年英国脱欧公投带来的不确定性和预期冲击对英国与欧盟及非欧盟国家贸易的影响，发现英国出口在公投前一年已开始下降，至2018年初对欧盟出口损失近25%。
Summary We analyse the effects of uncertainty and anticipation shocks associated with the 2016 Brexit vote as a treatment on trade between the UK and 14 EU and 14 non‐EU trading partners, using the synthetic control method (SCM). After controlling for exchange rate and GDP changes, UK exports to both groups of countries fell below those of the ‘synthetic Britain’, with much of the shortfall developing over the year prior to the referendum, following the 2015 Conservative general election win. The results indicate that UK exports to EU countries may have lost nearly 25% by early 2018, due to the Brexit shock, somewhat more than those to non‐EU countries. Imports from the EU and non‐EU countries also declined a little, although there is tentative evidence that UK consumers may have been avoiding countries with preferential trade agreements (PTAs) with the EU, and possibly turning towards the Commonwealth. Overall, the results confirm that policy uncertainty has a major effect upon trade and that uncertainty about supply chain costs is a potential explanation for at least some of the shortfall.