Asking open-ended questions, such as "What are your views on drug addiction?" allows for a wider range of responses from participants. Participants have the opportunity to expound on their views, feelings or attitudes toward a subject whereas with a close-ended question participants are only able to choose from a limited number of responses, which may not accurately depict their attitudes or feelings.
Response error is described by Sudman as "an error that occurs when respondents do not reveal their true opinions of a subject." Response error can negatively affect the results of a study and should be eliminated when possible. Open-ended questions allow for less response error because participants are less likely to forget the responses when they are responding freely, and it is less likely they will respond without reading the questions.
Secondary analysis plays an important role in the world of research. Secondary analysis is a way for researchers to look at existing research studies and gather new conclusions or information from them that had not previously been found. Open-ended questionnaires are more readily used for secondary analysis because they contain demographic information, such as age, gender and employment, which are not included in close-ended questionnaires.
When you conduct research, there are many sensitive topics that may come up, such as drug addiction, sexual behaviors or other topics that may make some respondents uncomfortable. Research has shown that open-ended questionnaires are better for eliciting sensitive information from respondents than close-ended questionnaires. Therefore, if a researcher is conducting a study on drug use, it would make more sense to use an open-ended questionnaire.