Supply chain disruptions have recently been at the center of both academic and policy debates. After reviewing some of the emerging literature on supply chain disruptions, we discuss the role of buyers' sourcing strategies in mediating responses to such shocks. We focus on two dimensions of a buyer's sourcing strategy: relationality (the extent to which the buyer concentrates its sourcing in a few core suppliers) and just-in-time. On the one hand, theoretical models of sourcing suggest that these are complementary practices and their adoption should be positively correlated in the data. On the other hand, the two dimensions have opposing implications for supply-chain resilience to shocks. We borrow an empirical proxy for a buyer's relationality from Cajal-Grossi et al. (2023) and introduce a new proxy for a buyer's adoption of just-in-time inventory systems. Using data from the apparel global value chain we compute the two proxies and present three results: (a) the variation in both relationality and just-in-time is mostly explained by across-buyer variation, rather than product or country variation, (b) consistent with the theoretical analysis in Taylor and Wiggins (1997), relationality and just-in-time are highly correlated with each other across buyers, (c) at the onset of the global Covid-19 pandemic, buyers' overall sourced values declined relatively less for relational buyers but not for buyers with just-in-time inventory systems.

供应链中断最近成为学术和政策辩论的中心。在回顾了一些有关供应链中断的新兴文献后，我们讨论了买家的采购策略在调解此类冲击的反应中的作用。我们关注买家采购策略的两个维度：关系性（买家将采购集中于少数核心供应商的程度）和准时化。一方面，采购的理论模型表明这些是互补的实践，它们的采用应该与数据呈正相关。另一方面，这两个维度对供应链抵御冲击的能力具有相反的影响。我们借用了买家关系的经验代理卡哈尔-格罗西等人。（2023）并为买方采用即时库存系统引入新的代理。使用来自服装全球价值链的数据，我们计算两个代理并呈现三个结果：(a)关系性和及时性的变化主要由跨买家的变化来解释，而不是产品或国家的变化，(b) ) 与Taylor 和 Wiggins (1997)的理论分析一致，买家之间的关联性和及时性彼此高度相关，(c) 在全球 Covid-19 大流行开始时，买家的整体采购价值下降相对较少的关系买家，但不适用于拥有即时库存系统的买家。