The market work behavior of adult women in the United States has changed radically in the last several decades as a greater and greater share spend substantial time in the labor market. Despite this large time reallocation, comparatively little study has been devoted to the structure of the resulting work activities or to changes in that structure. In this study, data from the Mature Women's Cohort of the National Longitudinal Survey is used to characterize the life cycle evolution of work structure from an annual perspective. Work is partitioned into four categories based on two work dichotomies: full- or part-time weeks and full- or part-time hours per week. Three "part-time" work possibilities exist in this framework: i) part-time weeks and full-time hours per week. ii) full-time weeks and part-time hours per week, and iii) part-time weeks and hours per week.
The analysis adopts a supply and demand framework. Employers have preferences for an employee's weeks per year and hours per week. Employer demands for weeks per year are likely to be influenced by seasonal and cyclical factors, while hours per week are likely to be affected by production and customer technologies. High training costs are likely to induce both greater weeks and greater hours per week. Similarly the worker is likely to have preferences over the total time she supplies to the firm and how these are divided into weeks and hours per week. For women with small children, the structure of the school year and of the school day are both likely to be important.
The National Longitudinal Survey of Mature Women provides a valuable data set for the investigation of recent trends in the structure of female work activity, including the growth of part-time work. It offers a quarter of a century of detailed information on approximately 5000 female respondents 30 to 44 years of age in the first year (1967), and provides an important opportunity to explore the dynamics of work choices from midlife to the eve of retirement for the entire sample and into the retirement period for a substantial subset of the sample during the time of this great transition. The study focuses on the 1967-1989 period at the end of which time the respondents were 52 to 66 years of age.