Suppose the sample has \(n\) data points, each denoted \(x_i\) where \(1\le i\le n\).
First compute the mean: \(\overline x=\displaystyle\frac1n\sum_{i=1}^nx_i\).
The sample standard deviation is then
\(\displaystyle\sqrt{\sum_{i=1}^n\frac{(\overline x-x_i)^2}{n-1}}\)
