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Forest Plot CI — SCE Medical Oncology MCQ

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EasyClinical Trials & StatisticsForest Plot CISCE Medical Oncology

A researcher interprets a forest plot where one study has a wide CI crossing HR 1.0 while another has a narrow CI to the left. What determines CI width?

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Correct answer: C — Sample size and event rate — larger studies produce narrower CIs and contribute more weight to the pooled estimate

Forest plots: CI width reflects precision. Larger studies (more events) → narrower CIs → more weight. I² quantifies between-study heterogeneity. Diamond = pooled weighted estimate.

Reference: JRCPTB; Cochrane Handbook; Higgins et al BMJ 2003