The Comparative Advantage of Firms
利用印度制造业数据，发现企业进入新行业时倾向于选择与其现有投入结构相似的行业，投入能力是决定企业比较优势的关键因素，投入市场的进入壁垒相当于10.5个百分点的关税。
Multiproduct firms dominate production, and their product turnover contributes substantially to aggregate growth. Theories propose that multiproduct firms grow by diversifying into products which need the same know-how or capabilities, but are less clear on what these capabilities are. Input output tables show firms co-produce in industries that share intermediate inputs, suggesting input capabilities drive multiproduct production patterns. We provide evidence for this in Indian manufacturing: the similarity of a firm’s input mix to an industry’s input mix predicts entry into that industry. We identify the direction of causality from the removal of size-based entry barriers in input markets which made firms more likely to enter industries that were similar in input use to their initial input mix. We rationalize this finding with a model of industry choice and economies of scope to estimate the importance of input capabilities in determining comparative advantage. Complementarities driven by input capabilities make a firm on average 5% (and up to 15%) more likely to produce in an industry. Entry barriers in input markets constrained the comparative advantage of firms and were equivalent to a 10.5 percentage point tariff on inputs.