Network externalities in supermarket retailing
利用消费者和供应商内部化网络效应的不对称能力，提出并检验了多产品零售市场中网络效应的新测试，发现零售利润随品种增加而上升、批发利润下降，支持超市零售中存在正向双边网络效应。
Supermarkets face a two-sided demand for shelf space: consumers demand variety and suppliers demand shelf space. We exploit the asymmetric ability of consumers and suppliers to internalise network effects to derive a novel test of network effects in multi-product retail markets. Because consumers fully internalise network effects but suppliers cannot, retail margins rise and wholesale margins fall as variety increases. We test this hypothesis using retail scanner data for a ‘shopping basket’ of items from competing retailers using a structural model of retail variety and vertical pricing. Our results support the existence of positive, two-sided network effects in supermarket retailing. , Oxford University Press.