| Cohort (birth year of twins): | 1994 | 1995 | 1996 | TOTAL |
|---|---|---|---|---|
| Contacted to arrange visit | 366 | 347 | 279 | 992 |
| Visit completed | 303 | 285 | 250 | 838 |
| Percentage of contacted families visited | 82.8% | 82.1% | 89.6% | 84.5% |
| Data in the dataset (test data present for both twins) |
302 | 281 | 248 | 831 |