The standard deviation represents the degree of dispersion of sample data. The standard deviation is the square root of the variance of the sample mean. The standard deviation is usually relative to the average value of sample data, usually expressed by M SD, which indicates how far the observed value of a certain data of the sample is from the average value. As can be seen from this, the standard deviation is influenced by the extreme value. The smaller the standard deviation, the more aggregated the data; The greater the standard deviation, the more discrete the data.

The standard deviation depends on the test. If a test is an academic test with a large standard deviation, it means that the dispersion of students' grades is large, which can better measure students' academic level.

Extended data:

The standard deviation, also called mean square deviation in Chinese environment, is the square root of the arithmetic mean value deviating from the mean square, and is expressed by σ. The standard deviation is the arithmetic square root of variance. The standard deviation can reflect the degree of dispersion of the data set. The standard deviation of two sets of data with the same average value may be different.

Standard deviation _ Baidu Encyclopedia?