A dataset of daily caloric intake (kcal) for 200 adults is positively skewed. Which measure of central tendency should be reported and why?
- A Mean, because it uses all data points
- B Mode, because it is the most common value observed
- C Median, because it is resistant to extreme values in skewed distributions ✓
- D Geometric mean, because caloric data is ratio-scale
Correct answer: C. Median, because it is resistant to extreme values in skewed distributions
Explanation
In positively skewed distributions, the mean is pulled towards the right tail by extreme high values, making it an unrepresentative measure of the 'typical' individual. The median, being the middle value, is not affected by extreme outliers and better represents the central tendency. Mode is useful for categorical data. Geometric mean is appropriate for log-normally distributed data (e.g., antibody titres) but not specifically for the skewness reason cited here.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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