Institutional integration and productivity growth: Evidence from the 1995 enlargement of the European Union
利用1995年欧盟扩大时挪威未加入单一市场的自然实验，估计更深度一体化会使挪威地区年均生产率增长提高约0.6个百分点，且边缘地区和工业部门损失更大。
This paper studies the productivity effects of integration deepening. The identification strategy exploits the 1995 European Union (EU) enlargement, when all candidate countries joined the Single Market but one — Norway — did not join the EU. Our synthetic difference-in-differences estimates on sectoral and regional data suggest had Norway chosen deeper integration, the average Norwegian region would have experienced an increase in yearly productivity growth of about 0.6 percentage points. This method also helps determining the sources of heterogeneity, apparently inherent to integration, highlighting higher costs of the missed deeper integration for more peripheral regions and industrial sector.