Approach of respondents
Trained interviewers who use lap top computers for data entry visit the respondents at home. Interview and tests take one and a half hours approximately. To obtain additional data, respondents are asked to fill out a written questionnaire separately. After having obtained the consent of the respondent, a separate visit is made by a nurse interviewer to take clinical measurements (the "medical interview").
For the drawing of blood consent has to be given too. The respondents are asked to go to a hospital near by to have their blood drawn. If that is not possible the respondents are visited at home.
