Information was gathered from NCDS and BCS70 cohort members by interview and using a self-completion questionnaire. A major innovation was the use of computer-assisted, rather than paper-based, methods of data collection. CAPI (Computer Assisted Personal Interviewing) serves to improve the quality of the data collected, by simplifying the conduct of the interviews with complex filter structures. It also facilitates rapid production of clean data, because data can be edited on entry. Use of CAPI also simplifies coding of information about occupation, and answers to other open-ended questions where responses can be keyed in during the interview. The same method, CASI (Computer Assisted Self-Interviewing), was employed with the self-completion instrument, when the laptop computer was handed over to the cohort members themselves.

Following development work - including: pre-piloting qualitative interviews and a pilot based on traditional paper interview schedules and self-completion questionnaire all based on non-cohort member samples; and a CAPI/CASI ‘dress rehearsal’ pilot based on a cohort member sample - the survey instruments were programmed into a single CAPI/CASI instrument using Blaise 3 which was suitable for both NCDS and BCS70 cohort members. This was possible because over 90 per cent of questions were common to both cohorts. The major differences between the content of the NCDS and BCS70 surveys were: 

  • Reference dates for retrospective questions/histories. These were March 1991 for NCDS, and April 1986 for BCS70 - although NCDS cohort members who did not take part in the 1991 follow-up (NCDS5), where asked for details of qualifications gained since March 1981 (see below). 
  • The inclusion of additional questions for NCDS cohort members dealing with:
  • Children over the age of 16 years
  • Children absent from the household, but who were living with cohort member in 1991

Content of surveys

As noted above, the survey instrumentation was developed in consultation with those who have been involved with the design and analysis of earlier NCDS and BCS70 surveys, other research advisors and funders; and in accordance with the following principles: 

  • Relevance to the stage of life reached 
  • Continuity with previous surveys 
  • Comparability across NCDS and BCS70 
  • Compatibility with other surveys (eg: BHPS, the General Household Survey and the (US) National Longitudinal Survey of Youth)
  • In summary the content of the surveys is:

Household details

Household grid
Language spoken in the home


Current address
Intentions to move
Property inheritance
Housing history


Marital status
Relationship history


Pregnancy history
Lone parenthood
Adopted children
Partner’s children from a previous relationship
Children over 16 (NCDS only)
Absent formerly resident children (NCDS only)
Family activities
Demands of parenting

Family, Social Relationships & Support

Contact with family
Emotional support
Family Income
Other Income
Financial situation


Economic activity
Current job
Other paid work
Currently unemployed
Labour market histories
Partner’s job

Lifelong Learning

Current course for qualification
Assessment of current/most recent course
Other courses and training
No formal learning
Learning overview
Contact with information technology
Literacy and numeracy


General health
Long-term health conditions
Respiratory problems
Mental health
Seeing and hearing
Other conditions
Hospital admissions
Height and weight

Citizenship and Values

Involvement with organisations, voting behaviour and intentions, political alignment, trade union membership, religion, newspaper readership, car ownership, values, political activity


Your views - Attitude statements
How you get on with your spouse or partner
How you feel – GHQ12 General Health Questionnaire
Your skills
How you feel about your life so far
School exclusion and truancy
Contact with the police and crime
Use of illegal drugs