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    Help with statistical power?




    Hi, I'm doing a study looking at the ability of a test to detect a change in bacterial numbers pre- versus post-treatment [i.e. not treatment effect, but pilot study looking at efficacy of the test used]. I've done a chi-square test and got a significant result (p<0.05). However given that I have a small sample size of 10 patients, is my study considered underpowered? And how do i calculate the ideal sample size for such a study?

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    Re: Help with statistical power?

    hi,
    power should not be an issue here aa you have found an effect. (Power being the probability of detecting an effect).Given the small sample I would worry more about the reproducibility -i.e. if you repeated the test with a new sample of 10 would you see the same effect size?
    regards

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    Re: Help with statistical power?


    Quote Originally Posted by rogojel View Post
    hi,
    power should not be an issue here aa you have found an effect. (Power being the probability of detecting an effect).Given the small sample I would worry more about the reproducibility -i.e. if you repeated the test with a new sample of 10 would you see the same effect size?
    regards
    Ahh I see, that makes a lot of sense, thanks a lot!

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