Surveys or questioning involve using a questionnaire (data collection instrument) to ask respondents questions to secure the desired information. Questionnaires may be administered by mail, over the telephone, by computer, or in person. Limitations of surveys include opportunities for error in construction and administering of a questionnaire, expense, and time needed to conduct a survey. Respondents may not respond, may be unable to respond, or may give misleading responses.
Mail interviews can be used to collect large amounts of data and have a low cost per respondent. Respondents can see a concept, read a description, and think about it at their leisure. There is no interviewer bias. However, the questionnaires are not flexible, cannot be adapted to individual respondents, and generally have low response rates. The researcher has no control over who completes the questionnaire.