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Confidence interval crossing null — MRCPCH TAS MCQ

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ModerateStatistics and evidence-based medicineConfidence interval crossing nullMRCPCH TAS

A paediatric asthma trial reports risk ratio 0.82 with 95% confidence interval 0.61 to 1.10 for admission. What is the best interpretation?

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Correct answer: C — The result is not statistically significant at the 5% level

A confidence interval for a risk ratio that crosses 1 is not statistically significant at the 5% level. It does not prove equivalence, because equivalence requires a specific design and margin. The pearl is that confidence intervals convey both direction and precision.

Reference: The Science of Paediatrics MRCPCH Mastercourse; CEBM statistics principles; RCPCH Theory examination syllabi