Standard Deviation is simply a measure of dispersion in statistics. It gives an idea of how the individual data in a data set is dispersed from the mean. Standard deviation is defined as the square root of the mean of the squares of the deviations of all the values of a series taken from the arithmetic mean. It’s also known as the root mean square deviation.
The symbol used for standard deviation is sigma. While working with statistical problems, we come across with standard deviation quite frequently. Standard deviation is the measure of dispersion of the statistical data. Dispersion or variation is the property of the data to spread over a field. Dispersion measures the deviation of the data from its average or mean position. The degree of dispersion or variation is calculated by the means of measures of variation.