Standard deviation formula Sample standard deviation = arithmetic square root of variance = s = sqrt((x 1-x))? +(x2-x)？ +……(xn-x)？ ) /(n- 1)). population standard deviation = σ = sqrt ((x 1-x)? +(x2-x)？ +……(xn-x)？ )/n .

Detailed explanation and examples of standard deviation:

Standard deviation is a measure of the degree to which a set of values deviates from the average. A large standard deviation means that most values differ greatly from their average values; A smaller standard deviation means that these values are closer to the average.

For example, the average values of {0,5,9, 14} and {5,6,8,9} are all 7, but the standard deviation of the second group is smaller.