Researchers are often faced with the choice of using close ended or open ended questions in their questionnaires. Both forms have their pros and cons. However, open ended questions have some clear advantages in some situations. For instance, in preliminary researches, it makes infinitely more sense for the researcher to use open ended questions so that the respondent is not constrained in any form while answering.
A close ended questionnaire will force the answerer to pick an option from the provided list, and this always carries the risk of the real answer being left unrecorded. In cases where the respondents fail to understand the question, an open ended questionnaire gives them the liberty to quote appropriate answers and voice their concerns. Also, open ended questionnaires are more immune to the ‘fill in’ phenomenon where respondents just try to finish off filling the questionnaire by thoughtlessly picking up options.
However, there is a very clear disadvantage associated with open ended questions. Data acquires different forms and expressions in such cases, coding and analyzing which can become very difficult in case the variability is too high. The researcher has to weigh his analysis comfort with the reliability of the test instrument.