data(infert)
1. | Education | 0 = 0-5 years |
1 = 6-11 years | ||
2 = 12+ years | ||
2. | age | age in years of case |
3. | parity | count |
4. | number of prior | 0 = 0 |
induced abortions 1 = 1 | ||
2 = 2 or more | ||
5. | case status | 1 = case |
0 = control | ||
6. | number of prior | 0 = 0 |
spontaneous abortions 1 = 1 | ||
2 = 2 or more | ||
7. | matched set number | 1-83 |
8. | stratum number | 1-63 |