Re: [R] Wilcoxon Test and Mean Ratios

2012-09-21 Thread Henric (Nilsson) Winell
On 2012-09-20 21:07, Thomas Lumley wrote: On Fri, Sep 21, 2012 at 6:43 AM, avinash barnwal avinashbarnwal...@gmail.com wrote: Hi, http://en.wikipedia.org/wiki/Wilcoxon_signed-rank_test We can clearly see that null hypothesis is median different or not. One way of proving non difference is

Re: [R] Wilcoxon Test and Mean Ratios

2012-09-20 Thread Ben Bolker
Mohamed Radhouane Aniba aradwen at gmail.com writes: Thank you Thomas, So you think a t-test is more adequate to use in this case ? Rad No, because a t-test makes even stronger parametric assumptions. You were given more specific advice on stackoverflow

Re: [R] Wilcoxon Test and Mean Ratios

2012-09-20 Thread avinash barnwal
Hi, In Wilcoxon test , we look for medians rather than the means. Ratio of medians should be more coherent with P value. On Thu, Sep 20, 2012 at 6:30 PM, Ben Bolker bbol...@gmail.com wrote: Mohamed Radhouane Aniba aradwen at gmail.com writes: Thank you Thomas, So you think a t-test

Re: [R] Wilcoxon Test and Mean Ratios

2012-09-20 Thread peter dalgaard
On Sep 20, 2012, at 02:43 , Thomas Lumley wrote: On Thu, Sep 20, 2012 at 5:46 AM, Mohamed Radhouane Aniba arad...@gmail.com wrote: Hello All, I am writing to ask your opinion on how to interpret this case. I have two vectors a and b that I am trying to compare. The wilcoxon test is

Re: [R] Wilcoxon Test and Mean Ratios

2012-09-20 Thread avinash barnwal
Hi, http://en.wikipedia.org/wiki/Wilcoxon_signed-rank_test We can clearly see that null hypothesis is median different or not. One way of proving non difference is P(XY) = P(XY) where X and Y are ordered. On 9/20/12, peter dalgaard pda...@gmail.com wrote: On Sep 20, 2012, at 02:43 , Thomas

Re: [R] Wilcoxon Test and Mean Ratios

2012-09-20 Thread Thomas Lumley
On Fri, Sep 21, 2012 at 6:43 AM, avinash barnwal avinashbarnwal...@gmail.com wrote: Hi, http://en.wikipedia.org/wiki/Wilcoxon_signed-rank_test We can clearly see that null hypothesis is median different or not. One way of proving non difference is P(XY) = P(XY) where X and Y are ordered.

[R] Wilcoxon Test and Mean Ratios

2012-09-19 Thread Mohamed Radhouane Aniba
Hello All, I am writing to ask your opinion on how to interpret this case. I have two vectors a and b that I am trying to compare. The wilcoxon test is giving me a pvalue of 5.139217e-303 of a over b with the alternative greater. Now if I make a summary on each of them I have the following

Re: [R] Wilcoxon Test and Mean Ratios

2012-09-19 Thread Thomas Lumley
On Thu, Sep 20, 2012 at 5:46 AM, Mohamed Radhouane Aniba arad...@gmail.com wrote: Hello All, I am writing to ask your opinion on how to interpret this case. I have two vectors a and b that I am trying to compare. The wilcoxon test is giving me a pvalue of 5.139217e-303 of a over b with the

Re: [R] Wilcoxon Test and Mean Ratios

2012-09-19 Thread Mohamed Radhouane Aniba
Thank you Thomas, So you think a t-test is more adequate to use in this case ? Rad On Sep 19, 2012, at 8:43 PM, Thomas Lumley tlum...@uw.edu wrote: On Thu, Sep 20, 2012 at 5:46 AM, Mohamed Radhouane Aniba arad...@gmail.com wrote: Hello All, I am writing to ask your opinion on how to