From each figure, the mean is subtracted to get the difference (Y) in the next column. Each difference is squared to get (M) values on the next column. The average of the squared values gives the variance.
Standard Deviation Calculations
Standard deviation is measures by finding the square root of variance. In our calculations, the variance (VR) is 1.21microns. Using this variance, we calculate its square toot to get the value of our Standard Deviation (SDV) as 1.05microns