market research survey technique utilizing a list of questions answered separately by each survey participant. Questions may be closed-ended (answerable by checking one of several predetermined answers) or open-ended (requiring participants to answer in their own words). The answers to open-ended questionnaires are much more difficult to tabulate and analyze but provide more information than the surveyor might otherwise collect. Questionnaires are a good survey technique, because the cost (printing, distribution, collection, analysis) is low relative to that of other methods such as personal interviews , because participants can respond at their own convenience, because no interviewer bias is introduced, and because responses can be kept completely confidential. The disadvantages are that the results may be biased toward the opinions of those who chose to respond to the questionnaire versus all those who had been asked to respond, and the results may be distorted if the questions were misunderstood.