Sorry, but good on you people who looked it up! NCDS is National Child Development Study. It is a survey commissioned in 1958 which follows all babies born between March 3rd to March 10th.
They do regular health checks for medical research, ask about education, earnings, spending habits, family relationships, even personal questions about your sex life! Sometimes their research has led to breakthroughs in the understanding of the genetic underpinnings of medical conditions. Sometimes, based on the findings, the government has acted and given funding for education programmes or social matters.
Of course, as we approach 60 and beyond there will be fewer and fewer of us which is kind of why I was interested in finding anyone else on the survey.