Open-ended questions allow respondents to answer in any way they choose. An example of an open-ended question is asking the respondent to state five things that are interesting and challenging in the job. Another example is asking what the respondents like about their supervisors or their work environment. A third example is to invite their comments on the investment portfolio of the firm.
A closed question, in contrast, would ask the respondents to make choices among a set of alternatives given by the researcher. For instance, instead of asking the respondent to state any five aspects of the job that are interesting and challenging, the researcher might list 10 or 15 characteristics that might seem interesting or challenging in jobs and ask the respondent to rank the first five among these. All items in a questionnaire using a nominal, ordinal, or Likert or ratio scale are considered closed.