What are the benefits of open questions over closed questions?

Answer 1

Open questions permit the respondent to give a richer answer.Closed questions restrict the respondent to a limited choice of answer.

In a survey, I can ask AND restrict your choices to just these 2 items:

How do you feel today?

A. Good

B. Bad

Or I can add numerous choices, including asking you to tell me your own choice of description:

How do you feel today?

A. Happy

B. Sad

C. Angry

D Excited

E. Other -- [box, please specify the emotion that describes you today]

OR, I can include a box that allows for 1,000 characters and ask you:

Write about how you feel today (This is the most open method possible).

Answer 2

Open questions can collect information about issues which the researcher had not even considered. They can allow respondents to elaborate on their answers and to explain special circumstances which may not be covered by closed questions.