Questionnaires are restricted to two basic types of question:
Closed-ended (or “closed question”) is a question for which a researcher provides a suitable list of
responses (e.g. Yes / No). This produces mainly quantitative data.
Open-ended (or “open question”) is a question where the researcher doesn’t provide the respondent with a set answer from which to choose. Rather, the respondent is asked to answer "in their own words". This produces mainly qualitative data.