In a matched case-control study, 200 case-control pairs are enrolled. For a discordant pair where the case was exposed and the control was unexposed, the appropriate statistic used in the Mantel-Haenszel analysis is:
- A Standard Pearson chi-square applied to the 2×2 table
- B Fisher's exact test on the unmatched data
- C McNemar's odds ratio = f/g, where f and g are discordant pair counts ✓
- D Cox proportional hazards model
Correct answer: C. McNemar's odds ratio = f/g, where f and g are discordant pair counts
Explanation
In a matched case-control study, concordant pairs (both exposed or both unexposed) contribute no information about the association; only discordant pairs are informative. The McNemar OR = f/g, where f = pairs with case exposed/control unexposed and g = pairs with case unexposed/control exposed. The standard chi-square ignores matching and inflates degrees of freedom. Cox models are used in cohort/survival data.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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