Issues in teaching about computing the standard deviation

The standard deviation is the most commonly reported measure of variability for a group of measurements. It is used as a descriptive statistic to indicate the degree of homogeneity or heterogeneity present in a given group of measurements and as an estimate of a population parameter. It is also used as a component of formulas for other statistics such as the standard error of estimate and the standard error of measurement. This article discusses issues in teaching students about computing the standard deviation in both of these contexts. The standard deviation does not identify the same quantity in all of these situations.