nav[aria-label="Primary Navigation"] { padding: 0; & ul { list-style: none; width: 100%; display: flex; flex-direction: row; justify-content: start; align-items: start; gap: 30px; padding: 0; & li { margin: 0; } & ul li { list-style: none; } } }

337749_en-US

liliconcom

Power function, uneven sample number

I have a data set made up of few samples Group #1 (8 samples) and Group #2 (2 samples). I am performing a t test to identify the mean differences. As the sample size is small I would like to understand (1) what the power is currently (2) what number of samples for Group #2 would I need to be 95% confident of the result. I attached the data set.

Jack

Analytics

Re: Power function, uneven sample number

Retrospecitive power analysis is discouraged but you can use your data to explore power for prospective case. I assume that you used the Oneway platform. See this page for details about the power analysis available in that platform.

Re: Power function, uneven sample number

Thanks Mark, am I right in thinking that n=2 is literally too small to determine the power function. I plugged in the data and it stated "Some Probability Calculations Signaled Errors", it works with n=3

Re: Power function, uneven sample number

Yes. So use n > 2. Aren't you using this retrospective power analysis to prospectively determine the minimum sample size? That number is likely greater than two.

Comments

There are no comments yet