Question types and response options

What a questionnaire is for

• A questionnaire collects data to answer an investigative question (e.g. "What do students think of the canteen?").
• Every question should help answer that purpose — if a question does not, cut it.

Open and closed questions

• Open question — the respondent writes their own answer.
  • Gives rich, detailed replies, but is hard to summarise and compare.
• Closed question — the respondent picks from given options.
  • Quick to answer and easy to analyse (you can count and graph the options), but only as good as the options you provide.

Response formats for closed questions

• Dichotomous — exactly two options (Yes / No).
• Multiple choice — pick one from several.
• Checklist — "select all that apply".
• Rating (Likert) scale — a scale of agreement or frequency:

• Numerical — a number (age, how many days).

Good response categories: exclusive and exhaustive

• Options must be mutually exclusive — no answer fits two categories.
• Options must be exhaustive — there is a category for everyone (add "Other" or an open end if needed).

• The classic error is overlapping number ranges like $0\text{–}10,\ 10\text{–}20$ — age 10 fits both. Use $0\text{–}9,\ 10\text{–}19,\ 20\text{–}29,\ 30+$ instead.