In a case-control study on obesity and type 2 diabetes, the matched odds ratio is calculated using the McNemar's test rather than the standard chi-square test. This is because:

• A The outcome is continuous rather than binary
• B The exposure is a rare event
• C More than two exposure categories are present
• D Cases and controls are paired and their data are not independent ✓

Explanation

McNemar's test is used for matched paired categorical data where observations are not independent, such as in individually matched case-control studies. Standard chi-square assumes independence of observations, which is violated when cases and controls are matched on confounders. McNemar's test uses only discordant pairs (where exposure status differs between the case and its matched control) to estimate the odds ratio.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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