Semicollusion

The notion 'semicollusion' refers to situations where firms collude in one (or several) choice variable(s) and compete in others. For example, firms collude on prices and compete on advertising. Although the notion `semicollusion' is not so often used explicitly, it turns out that the topic is covered extensively in the economic literature. Moreover, the phenomena 'semicollusion' seem to be present in numerous industries. The purpose of this survey is to explain how semicollusion works in theory, describe empirical studies of semicollusion, and discuss the possible welfare effects of semicollusion.