In a dataset of birth weights from a rural block, most values are high but a few very low birth weight babies pull the curve to the left. Which relationship between the measures of central tendency is expected?
- A Mean is greater than median, which is greater than mode
- B Mean equals median equals mode
- C Mean is less than median, which is less than mode ✓
- D Mean lies between median and mode
Correct answer: C. Mean is less than median, which is less than mode
Explanation
In a negatively skewed (left skewed) distribution the long tail points toward low values, so the mean is pulled down below the median, and the median lies below the mode: mean less than median less than mode. The reverse order holds in positive skew, which kills option A. Option B describes a symmetrical normal distribution where mean, median and mode coincide.
Reference: Mahajan's Methods in Biostatistics for Medical Students and Research Workers, 9th ed.
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