Trade policy uncertainty, organization of firms, and the form of international trade
利用中国加入WTO作为自然实验，研究发现美中贸易政策不确定性降低使美国从中国的进口增加，且对非关联企业贸易的影响约为关联企业内部贸易的两倍，差异主要源于沉没成本。
Abstract This paper investigates the hypothesis that lower trade policy uncertainty (TPU) reduces the share of intrafirm trade in total trade. A significant change in US‐China TPU occurred in 2001 when China joined the WTO, providing a natural experiment to test this hypothesis. Using a difference‐in‐differences approach with industry‐level US data, I examine the trade effects of this change. The results indicate that the reduction in TPU between the US and China led to a significant increase in both US arm's‐length and intrafirm imports from China compared to pre‐WTO levels. Notably, the effect of TPU on arm's‐length trade is approximately twice that on intrafirm trade, with the disparity largely attributed to sunk costs. A simple model of production location and ownership choice under policy uncertainty provides a conceptual framework for understanding these findings.