This page summarises data returns in the 8 Year parent questionnaire study.
Most of the figures in the tables below are based on information logged in the TEDS admin database. However, figures for 'data in the dataset' are based on the final analysis dataset itself. Discrepancies between returns and actual data arise because of logging errors, unusable data, and losses of data.
The figures shown in the table below are numbers of families (twin pairs).
| School cohort | 1 | 2 | 3 | 4 | TOTAL |
|---|---|---|---|---|---|
| Twin birth dates | Jan-94 to Aug-94 | Sep-94 to Aug-95 | Sep-95 to Aug-96 | Sep-96 to Dec-96 | |
| Original ONS sample | 3746 | 5664 | 5490 | 1910 | 16810 |
| Questionnaires sent | 2898 | 4790 | 4592 | 1661 | 13941 |
| Questionnaires returned | 1454 | 2379 | 2101 | 858 | 6792 |
| Percentage of questionnaires returned | 50.2% | 49.7% | 45.8% | 51.7% | 48.7% |
| Data in the dataset | 1447 | 2370 | 2087 | 858 | 6762 |