I have two series of trading profit results. I use the geometric mean to calculate the average in percent (CAGR). I would like to divide it by the standard deviation by combining the two series, but I´m having trouble calculating the combined standard deviation.
I found this thread, but it looks like it only works with arithmetic mean, not geometric:
Is there a way to calculate the combined standard deviation here?
I got the geometric mean and corresponding geometric standard deviation for two separate data series. I now want to calculate the geometric mean and geometric standard deviation of the combined data series, using only the two mean/stdev values (not the original data points). Example:
Geometric mean 1: 0.070
Geometric stdev 1: 0.051
Number of datapoints: 7
Geometric mean 2: 0.053
Geometric stdev 2: 0.049
Number of datapoints: 16
I know how to calculate the combined geometric mean, but how can I calculate the combined stdev from the above values?