ESDS Longitudinal provides: a web-based download service specialist user support (linking with specialist support provided by the Centre for Longitudinal Studies (CLS)) training and workshops a range of value-added data enhancements for a number of key UK longitudinal data collections, including the 1970 British Cohort Study (BCS70)

The BCS70 began when data were collected about the births and families of babies born in the UK in one particular week in 1970. The first wave, called the British Births Survey, was carried out by the National Birthday Trust Fund in association with the Royal College of Obstetricians and Gynaecologists. Its aims were to examine the social and biological characteristics of the mother in relation to neonatal morbidity, and to compare the results with those of the National Child Development Study (NCDS), which commenced in 1958 (held separately at the UK Data Archive under GN 33004). Participants from Northern Ireland, who had been included in the birth survey, were dropped from the study in all subsequent sweeps, which only included respondents from Great Britain. Since BCS70 began, there have been seven full data collection exercises in order to monitor the cohort members' health, education, social and economic circumstances. These took place when respondents were aged 5, in 1975 (held under SN 2666), aged 10, in 1980 (SN 3723), aged 16, in 1986 (SN 3535), aged 26, in 1996 (SN 3833), aged 30, 1999-2000 (SN 5558), aged 34, in 2004-2005 (SN 5585), and aged 38, in 2008-2009 (SN 6557).

The first two sweeps (at 5 and 10 years) were carried out by the Department of Child Health at Bristol University. At that time, the survey was known as the Child Health and Education Study (CHES). The 16-year survey was carried out by the International Centre for Child Studies and named Youthscan. A supplementary survey of head teachers (held separately under SN 5225) was also conducted at the time of the 16-year follow-up in 1986. The Social Statistics Research Unit (SSRU) became involved with the BCS70 study at this time, and eventually changed its name to the Centre for Longitudinal Studies (CLS), based at the Institute of Education, University of London.

With each successive attempt, the scope of BCS70 has broadened from a strictly medical focus at birth, to encompass physical and educational development at the age of 5, physical, educational and social development at the ages of 10 and 16, and physical, educational, social and economic development at 26 years and beyond.

Users registered with the Economic and Social Data Service (ESDS) have access to the BCS70 datasets via the download service or can analyse, visualise, subset and download selected data from the BCS70 via the online Nesstar software tool.

• BCS70 datasets: www.esds.ac.uk/findingData/bcsTitles.asp
• ESDS Nesstar Catalogue: nesstar.esds.ac.uk/webview/index.jsp

Users can register with ESDS at: www.esds.ac.uk/aandp/access/login.asp

The BCS70 data currently available via ESDS cover the birth data and all follow-ups up to 2008-2009. In addition to the full cohort studies, four sub-sample surveys have been carried out. The first two, carried out in 1972 and 1973 and collectively named the British Births Child Survey, (held under SNs 2666 and 2690) followed sub-samples of the original cohort at ages 22 months and 42 months.

The sub-samples consisted of all twins in the original cohort, the 'small-for-dates' and 'post-mature' births, and a 10 per cent random sample of the original cohort. In 1992, when the cohort members were aged 21 years, a 10 per cent sample survey (held under SN 4715) was carried out, that focused on adult literacy and numeracy problems as well as the transition from school to work. A fourth sub-sample survey is not currently available from the ESDS. This survey was carried out in 1977 when 1,917 non-respondents from the five-year survey were traced and interviewed in an attempt to assess the effect of non-response. Users should contact the CLS direct to discuss access to this material.

Data on live-in relationships lasting one month or more have been collected in all BCS70 sweeps from sweep 6 (age 30) as well as data on current live-in relationship at sweep 5 (age 23) and merged into a 'Partnership Histories, 1986-2008' file (SN 6941) to create one longitudinal dataset. New information will be added subsequently with each sweep. Similarly, the 'Activity Histories, 1986-2008' file (SN 6943) compiles data on work and non-work activities lasting one month or more collected in all BCS70 sweeps from sweep 5 (age 26) onwards.

ESDS also makes available county-level geographic data at 1981, 1996 and 2000 boundaries, together with linking variables for all respondents to the 1986, 1996 and 2000 BCS70 follow-up surveys. These county-level data are available only under special licence conditions.

There are a host of invaluable BCS70 resources available on the CLS web site, accessible via www.cls.ioe.ac.uk/bcs70

Users interested in longitudinal studies more generally, including other UK and non-UK birth cohort studies, may be interested in the timelines at www.esds.ac.uk/longitudinal/resources/international.asp

Users are also welcome to keep up to date with BCS70 and other longitudinal data developments via the ESDS Longitudinal JISCmail list www.jiscmail.ac.uk/lists/ESDS-LONGITUDINAL.html and/or by registering with the CLS.

ESDS user documentation for the BCS70 can be downloaded in the form of multi-volume user guides in PDF format from the Data Catalogue via www.esds.ac.uk/findingData/bcs70.asp.

See also the Survey Question Bank - 1970 British Cohort Study: www.surveynet.ac.uk/sqb/surveys/bcs70.asp

CLS: Key publications: cls.ioe.ac.uk/page.aspx?&sitesectionid=933 CLS: Flagship publications: cls.ioe.ac.uk/page.aspx?&sitesectionid=934 For further work on the BCS70, search the bibliography at: cls.ioe.ac.uk/Bibliography.aspx?sitesectionid=647