# Standard Deviation of a ratio (Percentage Change)

I have 2 data sets. The first data set, let's call it X has an average value of (Xmean) and stadndard deviation of (XSTD), the second set of data also has the average value of (Ymean) and standard deviation of (YSTD).I want to find out the standard error or standard deviation of a percentage change of data set 2 compared to 1. So I have (Ymean-Xmean)/(Xmean)*100. Now my question is, how to take into account the standard deviations for this percentage value?

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I suggest stats.stackexchange.com for this question. –  David Roberts Feb 6 at 9:31