Читать книгу The Handy Psychology Answer Book - Lisa J. Cohen - Страница 233

In order to characterize a sample, it is not only necessary to know the measures of central tendency, it is also important to know how much the individual members of the sample vary from each other and from the group mean. The variance of a sample is a measure of the average distance of any sample member from the group mean. The standard deviation is the square root of the variance. The standard deviation is an important component of many statistical tests.