TEDS Data Dictionary

7 Year Data Returns

Contents of this page:

Introduction

This page summarises data returns in various parts of the 7 Year study: parent questionnaire data (from phone interview or paper booklet); twin telephone test data; and teacher questionnaire data. For details of data collection, see the main 7 Year study page. Note that twin telephone test data were not collected from the 1996 cohort.

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.

Note that, at the time of this study, attempts were made to collect data from all apparently contactable families in the original ONS sample. This included inactive families (never returned data and never enrolled) who were later removed from the TEDS sample - see the 1st Contact page. All families who returned 7 Year data were active and therefore have remained part of the TEDS sample. The return rates are therefore calculated as a percentage of the current TEDS sample, making these returns comparable with those in later studies.

Returns of Twin Data

Twin data were collected by means of telephone interviews. Prior to the interviews, parental consent was collected, firstly by letter and subsequently by telephone. Twin data were not collected for twins born in 1996.

The figures shown in the table below are numbers of families (twin pairs).

Study cohort 1 2 3 TOTAL
Twin birth dates Jan-94 to Aug-94 Sep-94 to Aug-95 Sep-95 to Dec-95
Original ONS sample 3746 5664 1940 11350
Consents sent 3256 4862 1693 9811
Current TEDS sample 3265 4888 1660 9813
Consents sent to current TEDS sample 2998 4439 1511 8948
Parental consent given 2018 2701 1008 5727
Twin interviews completed 1939 2617 977 5533
Percentage of contacted families
with twin interviews completed, in the TEDS sample 		64.7% 59.0% 64.7% 61.8%
Data in the dataset 1883 2574 964 5421

Returns of Parent Data

For the 1994 and 1995 twin births (study cohorts 1 to 3), collection of parent data was preceded by collection of consents (both written and telephone). The parent data were then collected in some cases by telephone interview, and in other cases by parent-completed booklets.

For the 1996 twin births (study cohorts 4 and 5), the consent form was attached to the parent booklet so they were returned together. All data were collected by means of the booklet, not by telephone interview.

The figures shown in the table below are numbers of families.

Study cohort 1 2 3 4 5 TOTAL
Twin birth dates Jan-94 to Aug-94 Sep-94 to Aug-95 Sep-95 to Dec-95 Jan-96 to Aug-96 Sep-96 to Dec-96
Original ONS sample 3746 5664 1940 3550 1910 16810
Consents sent 3256 4862 1693 3090 1680 14581
Current TEDS sample 3265 4888 1660 2608 1524 13945
Consents sent to current TEDS sample 2998 4439 1511 2467 1416 12831
Consent given 2018 2701 1008 1566 886 8179
Parent data returned 1939 2594 924 1566 886 7909
Percentage of contacted families
returning parent data in the TEDS sample 		64.7% 58.4% 61.2% 63.5% 62.6% 61.6%
Data in the dataset 1926 2552 914 1562 881 7835

Returns of Teacher Data

Teacher data were collected by means of paper questionnaires, sent by post. Prior to sending the questionnaires, parents were asked (using the consent form) for consent specifically to contact the twins' teachers, and were asked 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).

Study cohort 1 2 3 4 5 TOTAL
Twin birth dates Jan-94 to Aug-94 Sep-94 to Aug-95 Sep-95 to Dec-95 Jan-96 to Aug-96 Sep-96 to Dec-96
Original ONS sample 3746 5664 1940 3550 1910 16810
Consents sent 3256 4862 1693 3090 1680 14581
Current TEDS sample 3265 4888 1660 2608 1524 13945
Consents sent to current TEDS sample 2998 4439 1511 2467 1416 12831
Parents gave consent to contact teachers 1771 2612 887 1487 843 7600
Percentage of contacted families giving teacher consent in the TEDS sample 59.1% 58.8% 58.7% 60.3% 59.5% 59.2%
Teacher questionnaires sent (pairs) 1771 2600 871 1443 841 7526
Teacher questionnaires returned for both twins 1493 2205 730 1015 720 6163
Teacher questionnaires returned for only one twin 101 114 42 109 30 396
Percentage of teacher questionnaires sent that were returned 87.2% 87.0% 86.2% 74.1% 87.4% 84.5%
Percentage of families sent consents (TEDS sample)
in which both teacher booklets were returned		 49.8% 49.7% 48.3% 41.1% 50.8% 48.0%
Paired data in the dataset 1470 2176 728 1014 721 6109
Unpaired data in the dataset 124 122 44 110 31 431