Questionnaire Surveys and Structured Interviews Direct questioning of people about topic. Requires systematic sampling procedures to enable generalization. Advantages Can be very specific. Questionnaires Permit large scale studies and greater generalizability. Easy, economical, more anonymous.
Interviews can be sensitive to understanding of question and to nuances of response.
Good question design demanding. Pre testing necessary. Questionnaires Less investigator control. Questions may be misunderstood. More open ended, less directive interview style.