We examine some of the factors that might influence the quality of information produced in discussion groups on the internet, such as USENET and the WELL. In particular, we look at the impact of various different pricing structures, and compare regimes in which anonymity is enforced with regimes...

Firms selling multiple quality-differentiated products frequently alter their product lines when a competitor enters the market. We present a model of multiproduct monopoly and duopoly using a general `upgrades` approach that yields a powerful analytical framework. We provide a simple...

We present a general Cournot model in which each firm may sell multiple quality-differentiated products. We use an upgrades approach, working not with the actual products, but instead with upgrades from one quality to the next. The properties of single-product Cournot models carry over to the...