A study of hours devoted to a graduate course outside of classroom time generates a mean score of 90 with a standard deviation of 20. The mean age of the students was 31 with a standard deviation of 5 years. What is the relative dispersion of the two data sets?

Question

A study of hours devoted to a graduate course outside of classroom time generates a mean score of 90 with a standard deviation of 20. The mean age of the students was 31 with a standard deviation of 5 years. What is the relative dispersion of the two data sets?
        A. 2.22%; 1.6% 	
	B. 22.22%; 16.13% 	
	C. 34.44%; 20% 	
	D. Not calculable without additional data

PsyDAG · Answer

Relative dispersion, sometimes called the coefficient of variation, is the result of dividing the st. dev. by the mean, hence it is dimensionless (it may also be presented as a percentage). So a low value of relative dispersion usually implies that the st. dev. is small in comparison to the magnitude of the mean, as in a st. dev. of 6cm for a mean of 4m would give a figure of 0.015 (1.5%) whereas with a mean of 40cm it would be 0.15 or 15%.