Control charts usually present a graphic display of process stability and/or instability with time, from which the you can determine mean and standard deviation.

This adds one standard deviation to the value in the cell above it. Highlight this cell and press "Ctrl-C" to copy it. Then click on the cell below it and press "Ctrl-V" to paste the formula.

As an example of a standard deviation calculation, we can look at the S&P 500 during the first six months of 2024, which would be a formula for a sample, since it's a limited period.

M. Wood, M. Kaye, N. Capon, The Use of Resampling for Estimating Control Chart Limits, The Journal of the Operational Research Society, Vol. 50, No. 6 (Jun., 1999 ...