Confidence interval of difference between two means (half normal distribution)

#1
Hello,

I understand how to calculate the standard deviation for the difference between two means for normally distributed data, but please can you tell me if the same formulae should be used if both sets of data are half-normally distributed (i.e. each set of data being half a bell curve). Should I still use the attached formula? (I took a screenshot of the normal formula for standard deviation of the difference of two means)

Many thanks!

mnbvmnbv

p.s. I've tried googling for many hours but the answer doesn't seem to be out there (maybe it is obvious that the attached formula can be used??)
 

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