Table 1 Employment characteristics of 1101 cases and 1101 controls.
| Cases | Controls | |
|---|---|---|
| Age at start of employment (years) | ||
| Mean | 37.2 | 37.1 |
| Median | 37.7 | 37.7 |
| SD | 8.4 | 8.4 |
| Range | 15–50 | 15–50 |
| Year of recruitment | ||
| Mean/median | 1957 | 1957 |
| Range | 1946–91 | 1946–91 |
| Duration of employment (years) | ||
| Mean | 11.5 | 12.5 |
| Median | 9.7 | 10.6 |
| SD | 9.7 | 10.7 |
| Range | 1 month–40 years | 1 month–40 years |
| Age on leaving* (years) | ||
| Mean | 49.1 | 50.0 |
| Median | 50.9 | 51.7 |
| SD | 12.6 | 13.7 |
| Range | 20–65 | 17–66 |
*Some individuals were employed for two or more separate periods; hence the mean age at leaving is longer than the sum of the mean at start and mean duration of employment.