What you'll learn
Methods that gather data without manipulating variables.
Key ideas
- Observations, questionnaires and interviews (self-report).
- Correlations show a relationship (positive/negative) but not cause.
- Case studies examine one person or group in depth.
- Sampling: random, opportunity and systematic.
Exam tips
- Remember correlation does not prove causation.
- Weigh the strengths and weaknesses of each method.
Common mistakes
- Claiming a correlation proves cause.
- Confusing sampling methods.