STDDEV
Standard deviation, often abbreviated as stddev, is a statistic that measures the amount of variation or dispersion in a dataset. It indicates how far individual observations tend to be from the mean, providing a sense of the data’s spread.
There are two common forms. The population standard deviation, σ, is defined as sqrt( (1/N) Σ (xi − μ)² ), where
Stddev relates directly to variance, which is the average of the squared deviations from the mean. The
Calculation can be done by hand or with software. In practice, software packages may use different denominators