All eligible study members were contacted.
| Provided information | 3,307 | ||||||
| Cumulative total of deaths | 286 | ||||||
| Cumulative permanent refusals | 124 | ||||||
| Temporarily living abroad | 70 | ||||||
| Cumulative emigrated | 436 | ||||||
| Failure to contact | 1,139 | ||||||
A postal questionnaire was sent to all cohort members to ask about marriage, fertility, health, smoking, employment, training and further education and earnings. Health visitors attempted contacts and data collections with non-respondents.
Instructions are given at the head of each form.