50 minutes. Self-marked. 12 marks. Write your answers, open the model answer, then tick each mark you earned honestly. Nothing is sent or stored.
Scenario (invented)
A social-media post reads: “Loneliness is as deadly as smoking 15 cigarettes a day — scientists have proven it. Join our friendship app to live longer!” The post links to a study reporting an odds ratio of 1.26 (95% CI 1.12 to 1.42) for death among lonely adults.
Task 1 (2 marks)
State the percentage difference in odds and the width of the interval.
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Task 2 (3 marks)
Interpret the odds ratio and interval in plain language, avoiding the word “proven”.
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Task 3 (3 marks)
Give three problems with the post.
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Task 4 (4 marks)
Write an evidence card for the claim “loneliness is linked to higher odds of death”, and say which of the four intervention approaches from M5.L4 the app seems to use and what you would need to see before believing it works.
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Rubric and model answer
Task 1 (2 marks)
(1.26 − 1) × 100 = 26% higher odds. Width = 1.42 − 1.12 = 0.30.
Task 2 (3 marks)
Lonely adults had about 1.26 times the odds of death of others; the interval 1.12 to 1.42 lies above 1, so no association is incompatible, and the true value could plausibly lie anywhere in it. It is an association, not a demonstration of cause.
Task 3 (3 marks)
Any three: “proven” is too strong; observational data cannot rule out reverse causation or a third factor; the comparison with 15 cigarettes is not in the study and is not supported by the reported odds ratio; the post sells a product and offers no evidence it works; odds is not probability.
Task 4 (4 marks)
Claim: loneliness is associated with higher odds of death. Mechanism (proposed): stress and fewer health-supporting behaviours. Best evidence: pooled observational studies with an average increase of 26% in odds (Holt-Lunstad and colleagues, 2015). Strength: Moderate for association, Low for cause. The app seems to “increase opportunities for contact”. Evidence needed: a randomized comparison showing reduced loneliness and then outcomes.
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