What you'll learn
How to design a good questionnaire and gather reliable data.
Question types
- Open questions: free response — rich but hard to analyse.
- Closed questions: fixed options — easy to analyse and compare.
- Response classes should be non-overlapping and cover all possibilities.
Good practice
- Keep questions clear, short and unbiased. Avoid leading questions, overlapping classes and personal/embarrassing questions.
- Run a pilot survey to test the questionnaire before the main study.
Sources of bias
- Leading or ambiguous wording, non-response, and unrepresentative samples.
Exam tips
- When asked to improve a question, name the fault (e.g. 'overlapping classes' or 'leading') and rewrite it.
- Provide a response box with non-overlapping ranges.
Common mistakes
- Response classes that overlap (e.g. 0–10, 10–20).
- Forgetting an option for 'more than' the top value.