## How to divide standard deviations?

I am trying to work out the standard deviation of a percentage change. I have the mean baseline value ‘a’ and the mean follow up value ‘b’, along with their standard deviations. Percentage change is: (b-a)/a I am able to calculate the SD of (b-a): The formula for which I obtained from: https://en.wikipedia.org/wiki/Propagation_of_uncertainty However, I … Read more