This paper develops a simple stochastic job matching model and uses it to derive a set of testable restrictions on the conditional probability with which a worker will be observed to change jobs over time. The restrictions describe the manner in which this probability varies with observable characteristics-i-current wage, labour market experience, tenure on current job, and past mobility. Econometric methods are also discussed, and some illustrative calculations provided. 1.

The paper provides analysis of 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 below what their current alternative offers; success is rare and rewarded highly. The implied distribution of earnings must have positive skewness.