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Thread: Question- student paired sample t test, wilcoxon signed rank test

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    Question- student paired sample t test, wilcoxon signed rank test




    Hi,

    I have samples that are not expected to be normally distributed, I treat them with and without a compound and perform statistical analysis. I perform the Wilcoxon signed rank test that is for samples that are not normally distributed.
    However, in some of my tests I do not have enough samples and I have therefore performed student paired sample t test instead. So my question is: If you perform student paired sample t test on samples that are not expected to be normally distributed are you then less likely to get a low p-value ( a significant different in the samples). So if you get a low p value(statistical significance), can you think that "oh, this is really significant since even the test that assumes normal distribution (which our samples are not) gives us a statistical significant p-value between the samples".

    Anyone follow me on this? :-) Hope someone can comment and help me!

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    Re: Question- student paired sample t test, wilcoxon signed rank test

    What is your sample size?


    Tests


    Ttest analog Wicoxon rank sum
    paired ttest analog Wilcoxon sign rank


    Your question is whether your run a ttest on skewed data, what affect it may have on the pvalue compared the pvalue for the analog test?
    Stop cowardice, ban guns!

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    Re: Question- student paired sample t test, wilcoxon signed rank test

    Thanks for your reply. Paired sample t test is not the same test as wilcoxon rank sum. Wilcoxon rank sum is for samples from different origin, where you cannot expect the same variations.
    Paired sample t test is for normally distributed samles
    wilcoxon signed rank test is for not normally distributed samples

    samples from the same origin, treated with and without a compound.

    I have only 3 and 5 samples

    Quote Originally Posted by hlsmith View Post
    What is your sample size?




    Tests


    Ttest analog Wicoxon rank sum
    paired ttest analog Wilcoxon sign rank


    Your question is whether your run a ttest on skewed data, what affect it may have on the pvalue compared the pvalue for the analog test?

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    Re: Question- student paired sample t test, wilcoxon signed rank test


    hi,
    maybe I misunderstand your situation, but the choice between a paired and a vanilla t-test is based on whether you have a way to build pairs for your before-after measurements. If you can not, or the pairs are arbitrary, then a paired t-test is not an option, simply because there are no pairs in your data.

    regards

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