A Questionnaire is a research instrument composed of a series of questions designed to gather information about a certain topic. It can be administered via paper and pencil, where respondents simply fill out a survey form and send it back by mail or other means. It can be administered by an interviewer, who asks a set of questions face-to-face or over the phone. It can also be computer-admnistered, such as when you are browsing a web site and a survey window pops up on the screen, inviting you to participate. However the mode of administration, information gathered from questionnaires are typically subjected to statistical analysis.
Questionnaires may have close-ended questions such as multiple choice or Yes/No items, or open-ended questions such as sentence completion items, or straightforward questions asking about opinions or thoughts of the respondent about a certain topic.