Group X has mean haemoglobin of 12 g/dL with SD of 1.2 g/dL. Group Y has mean haemoglobin of 8 g/dL with SD of 1.2 g/dL. To compare relative variability between the two groups, the appropriate measure is:
- A Standard deviation
- B Coefficient of variation ✓
- C Standard error of mean
- D Range
Correct answer: B. Coefficient of variation
Explanation
The coefficient of variation, calculated as (SD divided by mean) multiplied by 100, expresses variability relative to the mean and is unit-free, making it ideal for comparing dispersion between datasets with different means or units. Here CV of Group X is 10% while Group Y is 15%, showing greater relative scatter in Group Y despite identical SDs. SD alone cannot compare groups with different means, and SEM measures precision of the mean estimate.
Reference: Mahajan's Methods in Biostatistics for Medical Students and Research Workers, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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