We use data from a variety of sources. Our primary file on firm characteristics is the Robert Wood Johnson Foundation 1997 Employer Health Insurance Survey (EHIS). The survey collects a rich set of information about the firms: regardless of whether insurance is offered, establishment size, 10 broad industry groups, and most important from our perspective, the proportion of female workers and the percent of workers in each of four broad age categories. Starting from the full survey on 41 432 employers, we exclude results from government establishments, firms with no permanent full time employees, firms with missing values (mostly for income or industry type), and firms.
