The product life cycle in the commercial mainframe computer market, 1968-1982

We investigated product life cycles in the commercial mainframe computer ma rket. We rise hazard,models with time-varying covariates to estimate the pr obability of product exit and Poisson models to estimate the probability of introduction. We measure the importance of different aspects of marker str ucture, such as the degree of competitiveness, cannibalization, vintage, pr oduct niche, and firm effects. We find evidence of a relationship between t he determinants of product exit and product entry.