Before starting to write questions, you need to be familar with the different format of questions. Two formats can be used for questions: open and closed.
Open questions have no preformulated answers. Openly formulated questions are mainly used to allow an exploration of issues to generate some hypothesis which can be the case in qualitative research (1), focus groups, or the beginning of outbreak investigations (trawling questionnaires). Open questions should be used when there is no comprehensive range of alternative choices. Knowledge and attitudes on more complex issues can be explored and detailed or unexpected answers can be taken into account.
An example of an open question would be: "What do you think about measles vaccination?"
Open questions are more subject to the influence of the interviewer bias than closed questions. In addition, it is very time-consuming and cumbersome to code and analyse open questions as well to make comparisons between groups.
Closed questions give a choice of answer options. The advantages of closed questions are that they are simple and quick to answer, reducing the discrimination against the less literate respondents. They are easy to code, record and analyse. Comparisons can be done easily and the results are equally easy to report. However, they only allow a restricted number of possible answers which may result in a loss of information. As a possible compromise, a field „others" followed by space can be inserted in a closed question to provide a possibility for alternative responses.
See also Format of closed questions
1. Ritchie J. The Applications of Qualitative Methods to Social Research. In: Ritchie J, Lewis J,editors. Qualitative Research Practice. 1 ed. London: Sage Publications; 2003. p. 24-46