System Size, Lock-in and Network Effects for Patient Records

We examine empirically whether the size of a firm using a network affects the scope of its network usage, and consequently network effects and lock-in within the network. We use the example of hospital information exchange. We find that hospitals in larger hospital systems are more likely to exchange electronic patient information only within their system and less likely to exchange patient information externally. We show that hospitals are also more likely to exchange information externally if others hospitals also do so. This implies that the disinclination of large hospital systems to exchange data externally harms overall levels of network use. Our results highlight that makers of technology policy designed to encourage the optimal use of networks should consider regulating the behavior of network users as well as technology vendors.