This paper analyzes an occupation in which there is substantial uncertainty about individual performance and past performance is correlated with future outcomes. In equilibrium, only the young enter the occupation and only the successful stay on. The young are numerous and earn incomes well...

This paper develops a simple stochastic job matching model and uses it t o derive a set of testable restrictions on the conditional probabilit y with which a worker will be observed to change jobs over time. The restrictions describe the manner in which this probability varies wit h observable...

This paper studies the evolution of a competitive industry in which a fixed number of firms reduce costs by innovating and by imitating their rivals' technologies. As the firms' technologies gradually improve, industry output expands and price falls. Technological leaders tend to rely on...

Firm numbers first rise, then later fall, as an industry evolves. This nonmonotonicity is explained using a competitive model in which innovation opportunities fuel entry and relative failure to innovate prompts exit; equilibrium time paths for price and quantity also share features of the data....

A model of advertising is presented in which consumption experience is an imperfect indicator of product quality. In equilibrium, neither price nor advertising signal the quality of newly introduced goods. Advertising of established products can be a signal of quality, but if it is, it must be...