Learn By Doing – Standard Deviation
The concept of standard deviation is less intuitive as a measure of spread than the range or the IQR. The following activity is designed to help you develop a better intuition for the standard deviation.
At the end of a statistics course, the 27 students in the class were asked to rate the instructor on a number scale of 1 to 9 (1 being “very poor,” and 9 being “best instructor I’ve ever had”). The following table provides three hypothetical rating data:
And here are the histograms of the data:
This document is linked from Measures of Spread.