This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Dispersion of data is measured by -a) Coefficient of correlationb) Rangec) Standard deviationd) Coefficient of variatione) Normal distribution curve 
Select and explain. 
A. a, B. c, C. ac, D. bcd
D: bcd
Answer: D: bcd 
Explanation: Measure of dispersion (Variation)

Absolute: Range, Quartile deviation, Mean deviation, standard deviation.
Relative: Co-efficient of range, co-efficient of quartile deviation, coefficient of mean deviation, co-efficient of variation.