A study of 100 schoolchildren reports mean height of 140 cm with SD of 15 cm. The standard error of the mean is:
- A 0.15 cm
- B 1.5 cm ✓
- C 15 cm
- D 150 cm
Correct answer: B. 1.5 cm
Explanation
The standard error of the mean equals the standard deviation divided by the square root of the sample size, here 15 divided by the square root of 100, giving 1.5 cm. It quantifies the precision of the sample mean as an estimate of the population mean and is used to construct confidence intervals. Confusing it with the SD itself, option C, is the classic error; the SD describes scatter of individual values around the mean, not the reliability of the mean.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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