Recent content by sgadag

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    P value after Geisser-Greenhouse correction

    Don't run the analysis. Just try to obtain the P value for an F-ratio of 20.25, df(num) = 1.391,. and df(den) = 2.783 in SAS. You will get 0.046. So why do these different software give a P value of 0.023 for the same parameters? There is something in the analysis once the GG correction is made...
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    P value after Geisser-Greenhouse correction

    The epsilon value Prism gave me with the GG correction was 0.6957. Yes, the original df values are multiplied by this value to get the modified dfs. The dfs w/o correction are 2, and 4, and so when you multiply them by 0.6957, you get 1.391 and 2.783. The F-ratio is unaffected by the GG...
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    P value after Geisser-Greenhouse correction

    Thanks for checking with SAS, @fed2. Appreciate it. With only Graphpad, there was a possibility (albeit remote) that there was a mistake, but not with three. Not sure what you mean by "it's you," though. It's me only in the sense that I don't know why the P-value for a given F-ratio and dfs is...
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    P value after Geisser-Greenhouse correction

    Actually, I just ran the same analysis using SPSS, and yes, it gives me a P value of 0.023 as well. So the halving of the P value when the GG correction is used is not just a Graphpad issue.
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    P value after Geisser-Greenhouse correction

    Hello @fed2, thanks for the reply. The result is not data-specific (I have tried it with other data sets too). But here is the data set that I initially found the issue with. It is just made-up data for the purpose of teaching the concept: I will try it with other software too. Thanks. sgadag
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    P value after Geisser-Greenhouse correction

    I have noticed that when Graphpad Prism does a sphericity correction using the Geisser-Greenhouse correction, it halves the P value for this source of variation (typically Treatments). For example, in the example I am working on, it calculates an F value of 20.25, with DF(num) = 1.391, and...