# Z statistic test

#1
When performing a z statistic test between two populations- Once you've taken a set of samples and find the sampling mean - do we use the size of the number of samples in the set of samples as the value n- Or do we use n as the number of items in one sample?

Thank you
0
5 months ago
#2
I think what youre referring to is
https://www.cliffsnotes.com/study-gu...ring-two-means
and in the denominator, each (known) standard deviations is scaled by sqrt(n) where n is the number of samples used to estimate the appropriate mean (as usual).

There is a clear worked example here
in each case 30 samples are used for each mean, so n=30. There are 60 samples in total, but each estimated mean uses 30, so the standard deviation of the population is divided by sqrt(30).
Last edited by mqb2766; 5 months ago
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