In a nutritional survey, birth weights have a mean of 3 kg with a standard deviation of 0.45 kg, while haemoglobin values have a mean of 12 g/dL with a standard deviation of 1.8 g/dL. To decide which variable shows greater relative scatter, the researcher should compute:

• A Standard error of the mean for both variables
• B Variance ratio of the two variables
• C Range for both variables
• D Coefficient of variation for both variables ✓

Explanation

The coefficient of variation, expressed as (standard deviation divided by mean) multiplied by 100, is a unit-free measure of relative dispersion. It allows comparison of variability between variables measured in different units, here kilograms versus grams per decilitre. Birth weight gives CV of 15 percent while haemoglobin gives CV of 15 percent, showing comparable relative spread despite very different absolute standard deviations. The standard error reflects precision of the mean estimate, not relative scatter.

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

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