This paper provides a theoretical synthesis of recent discussions of "learning by doing" and "investment in training" as alternative forms of human capital accumulation. These theoretical notions relate to essentially different phenomena; in particular, pace Becker and Mincer, "investment in training" does not completely encompass "learning by doing". The paper then develops a model in which human capital accumulation occurs via both "training" and "learning by doing". The joint training-learning model, since it is more general then "pure" models in which all accumulation occurs via either training or learning, avoids certain restrictive and seemingly implausible implications of either kind of "pure" model. However, the joint model also has implications that, while compatible with stylized facts about the life cycle, are sharper than those of either kind of pure model. (For example, the joint model implies that market time and earnings must rise early in the life cycle, while neither pure model without "corners" does so.) Finally, the notion of learning by doing provides a rationale for an empirical finding that has recently received attention, to the effect that the rate of depreciation of human capital is not constant, but rather depends on the extent to which it is used in market activities.

This paper sets up a general equilibrium model of a world of heterogeneous jobs and heterogeneous tastes, and uses the model to (i) analyze the effects of employer discrimination and (ii) predict the likely consequences of requiring "equal pay for jobs of comparable worth." It shows that employment of both women and men is likely to fall as a result of comparable worth. It also shows that when individuals' tastes are heterogeneous, neither comparable worth nor the simple model of compensating differentials on which it is based provides useful insights into wage determination. In particular, when tastes are heterogeneous, there is no reason to expect equal pay for jobs of "comparable worth" even in the absence of employer discrimination.

As has long been recognized in the literature, questions about the effects of unions on wages may be conveniently grouped under two headings, which, following Lewis (1983), I shall refer to as wage gaps and wage gains. The wage gap refers to the difference between the pay a worker would receive were he represented by a union in collective bargaining and the pay he would receive were he not so represented. The wage refers to the difference between the pay a worker actually receives and the pay he would receive in the absence of any unionization. (When negative, as might be the case for a worker who is not represented by a union, the wage gain may actually be a wage loss.) It has generally been agreed that it is not possible to measure union wage gains, and a host of empirical studies attest to a consensus that measurement of the wage gap, while not impossible, is certainly difficult. Estimating the wage gap is particularly difficult in analyses that use aggregate (e.g., industry or occupation) cross-section data: such data typically do not contain measures of the average wage paid to unionized or nonunionized workers (Wu and W, respectively) considered separately.' The most obvious solution to this problem is to obtain aggregate data in which measures of both Wft and W, are available. In the present paper, I analyze union wage effects using just such a data set. The main point of interest that emerges from the analysis is that, contrary to what seems to be a general consensus, it is indeed possible albeit with some stringent identifying assumptions to estimate union wage gains as well as union wage gaps.

Using experimental design, this research examines the impact of the nation’s first family cap policy, implemented in New Jersey, on the fertility behavior of welfare recipients. We explore whether the change in welfare parameters mandated by the policy induces differential impact among black, white, and Hispanic recipients. We examine if impacts are conditioned by racial‐ethnic group concentration. Results show that reduced welfare payments have contributed to a decline in births for black women. While we find a large response for blacks (on average), we find no response for blacks who live in geographic areas where they form a racial‐ethnic majority.