There have been 24 waves of data collected on the whole cohort between 1946 and 2018. In addition there have been smaller collections conducted on various sub-groups.

Data were collected by contacts with study members themselves as well as through questions answered by their parents, school teachers, school doctors and nurses, and youth employment officers.
Between the ages of 0 and 15 information was collected from the parent, most usually the mother.
Between the ages of five and 15 some information was collected from the study members themselves, usually in the form of cognitive tests.
Since the age of 16, information has been collected from interviews with study members. A future data collection is planned from 2019 - 2022.

In addition, information was also collected from five other administrative sources. Consent was given in each case in accordance with the prevailing ethical requirements:

• Reports of hospital admissions have throughout the study been checked with hospitals in order to obtain greater detail of diagnoses and care 

• Information on exposure to outside atmospheric pollution was derived from data on the geographical distribution of measures of amounts of coal burned for domestic purposes, using data from the Warren Spring laboratory for the years 1946, 1948, 1950, 1952, 1953, 1954, 1955, 1957 (i.e. at ages birth, 2, 4, 6, 7, 8, 9 and 11 years)

• Reports of examinations successfully passed were checked with awarding authorities

• Since 1971 all study members have been flagged on the National Health Service (NHS) Central Register Information so that details of death certification can be passed to the study

• The NHS Central Register also provides information on registrations of cancer diagnoses on the national Cancer Register

• Copies of the most recent mammograms for women cohort members were requested from regional screening centres in 1999
  
  

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