Why do markets boom and crash? Why do fads and social norms start and end? The answer is found in a branch of social science literature called “cascade theory.” Cascade theory explains the observable human behavior of imitation: following the actions of someone else simply because one has...

We extend the theory of tax incidence under Cournot-Nash oligopolistic competition to study the effects of an ad valorem sales tax on Web services (so-called Web Tax) that are provided free of charge to users, and produce advertising space sold to businesses. Ads are more valuable to advertisers...