We examine the role of differentiation among competitive local exchange carriers (CLECs) in nearly 1,200 U.S. cities in 1999 and 2002, before and after a valuation crash affecting communications firms. We test and reject the null hypothesis of homogeneous competitors. We also find strong...

The authors examine thirty years of computer industry market structure. Their analysis explains the persistence of dominant computer firms, their recent decline, and the changing success of competitive entry. It emphasizes the importance of technological competition between computer 'platforms,'...

This study analyzes the service offerings of Internet Service Providers (ISPs), the commercial suppliers of Internet access in the United States. It presents data on the services of 2089 ISPs in the summer of 1998. By this time many ISPs had begun to offer services other than basic access. This...

In this paper, the authors examine the development of the microcomputer market in the early 1980s. CP/M, a widely-adopted operating system, was orphaned by the user and the development communities. A new operating system, DOS, and a new hardware platform, the IBM PC, became the predominant...