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Thread: Power and sample size calculation for neuroscience

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    Power and sample size calculation for neuroscience

    Dear TalkStats,

    I have searched the forum but cannot find the answer I am looking for, if you could help that would be great!

    I am recording cells and their action potential frequency in two conditions (group 1 and group 2). (So it is a repeated measures.)

    How do I calculate the required sample size in order to detect a significant difference between the conditions? What is the required power?

    Is the equation:

    n = \frac{16 \sigma^2}{\Delta^2}+1

    where n is the sample size, \Delta is the expected mean difference and \sigma is the standard deviation of my sample?

    Questions on this:
    1. This is "the sample size that gives 80% power at the 0.05 level of significance (two-sided)". What does this mean?
    2. \Delta is something I choose and also depends on the type of data. If they are independent samples, then its \Delta=\mu_1-\mu_2. What if they are paired samples, how do I find the value of \Delta?
    3. \sigma - this is the standard deviation of my variable under which condition? Group 1? Group 2?

    Any help on this would be great!
    Last edited by lb5962; 03-09-2016 at 04:46 AM. Reason: typos

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