Design and results of the Women's Health Study.

The Women's Health Study was a methodological experiment carried out in Chicago. More than 1,000 women took part; a comparison sample of 100 men was also included. The sample was selected from two sources. Most of the women and all of the men were selected from an area probability sample that had been screened to identify women in the eligible age range; the rest of the women were selected from rosters at cooperating abortion clinics and were known to have had an abortion. Questionnaires based on the one used in the National Survey of Family Growth were administered to the sample; the questionnaire included items on abortion, sexual behavior, and illicit drug use. The experiment examined five variables: whether the questionnaire began with a series of medical questions or with questions on pregnancy; whether the interview was conducted by a nurse or field interviewer; whether the interview was done at the respondent's home or outside the home; whether the interviewer or respondent administered the questions; and whether the data were collected on paper or via computer. Of the five experimental factors, the one with the most consistent effect was the method of administering the questions. Self-administration significantly increased the reported number of sexual partners, sexually transmitted diseases, and the level of condom use compared to administration by an interviewer. Computer assistance occasionally interacted with the site of the interview to effect reporting. The other two experimental variables-the version of the questionnaire and the data collection staff-had few discernible effects. None of the variables affected reported drug use over the lifetime.