Complex Contagion in Viral Marketing: Causal Evidence from a Country- Scale Field Experiment
44 Pages Posted: 2 May 2022 Last revised: 24 Apr 2023
Date Written: April 24, 2022
The diffusion of new products and services among consumers is a foundational issue in marketing. Research on complex contagions in product diffusion suggests that individuals need social reinforcement from multiple sources before they are convinced to adopt new products or services. We develop a conceptualization of social reinforcement using an adoption force equation and then empirically test its causal foundation in a country-scale randomized controlled viral marketing field experiment. The experiment used a peer encouragement design in which a randomly sampled set of customers were randomly encouraged to share a coupon for a mobile data product with their friends. We analyze the data from our experiment using three different analysis methods to confront empirical challenges of causally identifying social influence in social networks. Across all three methods we consistently find robust evidence of social reinforcement: the contagion process can no longer be seen as independent cascades but instead a process in which signals from multiple sources amplify each other. While the effect of social reinforcement is quite large, we show that the ability to harness this amplification effect in a realistic setting may be limited when the marketer cannot directly control the messages that customers send to their friends.
Keywords: Complex Contagion, Word of Mouth, New Product Diffusion, Social Networks, Field Experiment, Social Influence
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