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Thread: Correlation significance critical values

  1. #1
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    Correlation significance critical values

    I've been trying to determine the critical value for a sample size of 168 but all the tables only indicate values up to 100 (most of them). Is there any link available where I can get a complete table which will show me the critical value for 168 for one and two tailed tests?
    Alternatively, what critical value do I use if the sample size is so big?
    Last edited by globaljaco; 01-15-2015 at 08:16 AM.

  2. #2
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    seanw's Avatar
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    Re: Correlation significance critical values

    As I recall, the t-statistic for significance of a Pearson's r is t = [r*sqrt(N-2)]/sqrt(1-r^2). For N = 168 you have df = 166 and hence a critical t-value of 1.974358 (found using R command qt(.975,166) -- we use .975 for a two-sided test, but you can substitute a 1 - a/2 in place of the .975 for any value of alpha). Then simply substitute N and t into the equation and solve for r; I got something in the neighborhood of r = +/- .15.
    Last edited by seanw; 01-15-2015 at 10:45 AM.
    - Sean W.

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    globaljaco (01-16-2015)

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