An unsettled issue in the literature relating to the relative wage effect of unions is the appropriate treatment of union status in a wage determination model. In the context of a three-equation model determining union membership and union- and nonunion-sector wage rates, this paper presents an instrumental variables (IV) procedure for estimating the parameters of the wage equations and a test of the exogeneity of union status using the Hausman specification test. An advantage of our IV procedure in comparison to the widely used inverse Mill's ratio procedure is that our procedure is a distribution-free estimator, whereas the inverse Mill's ratio estimator hinges in the assumption that the error term of the choice equation is normally distributed. Using data for a sample of middle-aged white workers, we estimate the parameters of the union and nonunion wage equations with both procedures. On the key question of the endogeneity of union status, the Hausman test decisively rejects the null hypothesis of exogeneity. The inverse Mill's ratio procedure, in contrast, provides coefficient estimates on the selectivity terms that fail to indicate evidence of sample selectivity in either sector.

A multiperiod, general equilibrium model of the labor market is developed in which risk-averse workers are faced with job-related uncertainty and labor turnover is costly. If a worker is unlucky and suffers a bad job match, he quits and joins another firm, hoping that he will like its work environment more. Because the quality of a job match is unobservable, workers cannot insure against the risk of a bad match. The firm provides implicit insurance against job dissatisfaction, typically by paying workers more than their net marginal products in their early years with the firm and less subsequently. Since the probabilities of the insured-against events (the quit rates over time) are affected by the amount of such insurance provided, this implicit insurance is characterized by moral hazard. Individuals quit when in the absence of insurance they would not. The equilibrium contract balances out efficiency in risk bearing with efficiency in turnover incentives. We show that the equilibrium contract is not (constrained) efficient and indicate why.

In Britain, female labor force participation rose steadily from the Second World War to 1977. To explain this, we estimate a pooled time-series, cross-section supply function for single-year age groups of women. The life-cycle pattern is explained quite well by the presence of children. At a second stage we try to explain the rising level of the cohort intercepts estimated at the first stage. Real wage growth may be an explanatory factor, as cross-section evidence suggests it should be. Finally, we point to the 15% rise in the relative pay of women in the mid-1970s caused by the Equal Pay Act. This did not cause the expected decline in the relative demand for female employees.