The relationship between age-earnings profiles and worker incentives is examined by contrasting wage and salary workers with the self-employed. It is argued that the steepness of wage and salary workers' age-earnings profiles reflects the desire to provide work incentives to those workers. Since self-employed workers do not face this agency problem, they are used as a benchmark to gauge productivity. Empirical support of the proposition is provided, and the effects of human capital accumulation are separated empirically from incentive effects. The most important conclusion is that under some strong assumptions, most of the slope in age-earnings profiles is accounted for by the desire to provide incentives, rather than by on-the-job training.

It is argued that the estimation techniques used by previous researchers to study rivalry in financial markets are inappropriate. The assumptions of both ordinary least-squares and Tobi analysis are violated when these techniques are used to analyze mobility and turnover data. To overcome the difficulties in the previous studies, we suggest a non-linear model (which is closely related to the Poisson model). This model is designed for describing frequency data and is not subject to the criticisms to which ordinary least-square and Tobut are subject.

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"This paper discusses two approaches that economists have taken in analyzing the timing of births. It formulates an empirical model appropriate for one of these approaches and demonstrates its usefulness using household survey data from Costa Rica. The hazard rate technique employed in this paper is a natural way of modeling a broad class of problems where the occurrence of an event is uncertain." The study also indicates that "historical data can be used to determine whether the strong trend in the relationship between regional mortality levels and the age at first birth is real or the result of inappropriate data. Additionally, data from other countries might be employed to determine whether the significant effect of male education levels on the risk of subsequent births is a general result. Finally..., the predictions of theoretical models dealing with the number and pace of births can be tested using data from younger women."