Nobody's innocent: the role of customers in the doping dilemma

To which extent high performances in professional sports are based on the use of illicit substances or other doping practices is extremely difficult to measure empirically. Game-theoretical approaches predict strong incentives to dope based on the interaction among athletes (prisoner's dilemma) or the interaction between some control organization and the athletes (inspection game). The role of stakeholders such as customers, sponsors, and the media is either ignored or only informally discussed. One might think that customers who are ready to withdraw their support after a doping scandal, would reduce the incentives to dope. We explicitly model the strategic interaction of such customers with athletes and organizers and strongly refute this (optimistic) conjecture. Customers even trigger doping by putting a threat on the organizers not to conduct serious doping tests. However, we show that this result can be altered by a change in the information structure. If transparency about doping tests is established, then there is a doping-free equilibrium. This has practical implications for the design of anti-doping policies, as well as for other situations of fraudulent activities.