Collect data values: (x_1, x_2, dots, x_n)
Compute the mean: (bar{x}=frac{1}{n}sum_{i=1}^{n} x_i)
Compute deviations from the mean: (d_i=x_i-bar{x})
Square deviations: (d_i^2=(x_i-bar{x})^2)
Compute sum of squared deviations: (sum_{i=1}^{n} (x_i-bar{x})^2)
Population standard deviation:
(sigma=sqrt{frac{1}{n}sum_{i=1}^{n}(x_i-bar{x})^2})
Sample standard deviation:
(s=sqrt{frac{1}{n-1}sum_{i=1}^{n}(x_i-bar{x})^2})