Returns of Parent and Twin Data
Parent and twin data were collected by means of booklets. Prior to sending the booklets, written consents were collected; booklets were not sent unless families had consented first.
The 9 Year data were only collected for the first two cohorts (twins born between January 1994 and August 1995), hence there are no data for the 1996 cohort.
The figures shown in the table below are numbers of families (twin pairs).
| School cohort | 1 | 2 | TOTAL |
|---|---|---|---|
| Twin birth dates | Jan-94 to Aug-94 | Sep-94 to Aug-95 | |
| Original TEDS sample | 3265 | 4888 | 8153 |
| Consents sent | 2846 | 4685 | 7531 |
| Consents returned | 1604 | 2473 | 4077 |
| Percentage of consents returned | 56.4% | 52.8% | 54.1% |
| Booklets sent | 1604 | 2472 | 4076 |
| Booklets returned (all three) | 1356 | 2029 | 3385 |
| Percentage of families that returned all three booklets | 84.5% | 82.1% | 83.0% |
| Partial returns (one or two booklets) | 27 | 29 | 56 |
| Parent data in the dataset | 1373 | 2044 | 3412 |
| Paired twin data in the dataset | 1357 | 2036 | 3393 |
| Unpaired twin data in the dataset | 12 | 16 | 28 |
Returns of Teacher Data
Teacher data were collected by means of booklets. Prior to sending the booklets, parents were asked (using the consent form) for consent specifically to contact the twins' teachers, and for the teachers' contact details.
For most families, both twins were taught by the same teacher. However, for some families the two twins were taught by different teachers, and this resulted in some returns of unpaired data.
The figures shown in the table below are numbers of families (twin pairs).
| School cohort | 1 | 2 | TOTAL |
|---|---|---|---|
| Twin birth dates | Jan-94 to Aug-94 | Sep-94 to Aug-95 | |
| Original TEDS sample | 3265 | 4888 | 8153 |
| Consents sent | 2846 | 4685 | 7531 |
| Parents gave consent to contact teachers | 1537 | 2332 | 3869 |
| Percentage of contacted families giving teacher consent | 54.0% | 49.8% | 51.4% |
| Teacher booklets sent (pairs) | 1529 | 2332 | 3861 |
| Teacher booklets returned for both twins | 1009 | 1731 | 2740 |
| Teacher booklets returned for only one twin | 170 | 195 | 365 |
| Percentage of booklets sent that were returned: | 71.6% | 78.4% | 75.7% |
| Paired data in the dataset | 1007 | 1734 | 2741 |
| Unpaired data in the dataset | 171 | 195 | 366 |