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Sample Size

Posted: Tue Jul 14, 2026 2:59 pm
by nelsonal
Hello,

I recently used Jamovi software. This is my first time using the software and I wanted to ask about the sample size.

I ran a power analysis to learn my sample size. It was a one-tailed test, and I entered a (0.05), power (80%), and effect size (0.33). It gave me a sample size N of 59.

I have been trying to learn if that my total sample size or sample size per group (e.g. N= 59, so I need 59 for Group A and 59 for Group B to a total of 118).

If you could please clarify that would be greatly appreciated.
Kindly

Re: Sample Size

Posted: Fri Aug 21, 2026 5:42 pm
by Bobafett
I can only get N=59 value if you run a power analysis for a one sample t-test i.e. when you wish to compare a singular group.

If you intended this power analysis to be for an independent t-test (i.e. 2x groups), then you would have a total N=230 i.e. each group would have n=115 participants.