In one line: A correlation says two things move together. Causation says one makes the other happen.
In summer, ice-cream sales rise and so do drowning accidents. They go up and down together — a strong correlation. But ice cream does not drown anyone.
Causation is a much stronger claim. Mixing the two up is one of the most common — and most tested — mistakes in psychology.
Memory hook: Move together ≠ cause. Always ask: could a third thing explain both?
Free preview
This is the free notes preview
You're reading the free notes. Aimnova Pro unlocks the full study experience — and you can try it free for 7 days:
- FlashcardsLock in vocabulary and key terms with spaced repetition.
- Practice questionsAnswer exam-style questions and get instant AI marking.
- Mock exams & past-paper vaultSit full mocks and see exactly how examiners award marks.
- Personalised study planA daily plan built around your exam date and weak areas.
Key idea: When two things correlate, there are three innocent explanations — before you jump to 'A causes B'.
Three reasons a correlation is not a cause
A third variable
Something else causes both. Hot weather drives ice cream AND swimming (so drownings).
Reverse causation
B might cause A, not A→B. Does stress cause poor sleep, or poor sleep cause stress?
Coincidence
With enough data, some things line up by pure chance.
Third variable · Reverse · Coincidence
Take a real headline: 'teens who use social media more are more anxious'. It is tempting to say social media causes anxiety. But anxious teens might use it more to cope (reverse), or loneliness might drive both (third variable). The correlation alone cannot tell us which.
Go further — higher-level insight: Only a true experiment can show causation. By changing one variable (the IV) while controlling everything else, an experiment rules out third variables and reverse causation. A correlational study never can — it can only flag a link worth testing.
Know your predicted grade
Take timed mock exams and get detailed feedback on every answer. See exactly where you're losing marks.
How this is tested: Causality is one of the four named concepts for Paper 2 Section B. A classic move is to give a correlational study and ask you to discuss it — the top answer spots that it cannot show cause, and names the third-variable / reverse-causation problems.
A study finds that people who eat more breakfast tend to get better grades. A newspaper reports: 'Breakfast boosts grades.' Discuss this study with reference to causality.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Common mistakes: 1. Accepting the causal claim. Spot that it's correlational.
2. Naming 'third variable' with no example. Give a plausible one.
3. No judgement. A [15] answer weighs and concludes.