Re: st: Nemenyi test

[Célia Dechavanne <celia_dv@yahoo.fr>]

Dear all,

Thank you for your answers. As I said I'm not a statistician.
I have just one quantitative variable (specific antibody measures) for 5 
groups (women primigravid/multigravid that are not infected/infected and 
a negative control). I just want to know if there is a difference of the 
antibody rate between the groups. As the number of women by group is 
small, I choose a KW to test if there is a difference between the 5 
groups. The p was <0.001. Now, I would like to know what is the group 
"responsible" for the difference, that's why I would like to perform a 
test 2 by 2. I thought that the Nemenyi test was the good one (advise 
from a statistician) but I didn't find anything to perform this test 
with Stata. Thus I perform a oneway, but there was no significant 
difference between the groups (2 by 2). This appears as illogical, so I 
guess that I realized a mistake choosing oneway. Am I wrong?
Thanks for your help and your patience

Celia

Le jeudi 29 août 14:19, David Hoaglin a écrit :
> Celia,
>
> If you are not approaching your analysis via multiple comparisons, and
> you want to compare the shift between the five groups, how do you
> define "shift"?  Perhaps equivalently, how do you define the "typical
> value" in a group?
>
> Is the behavior of the data within the groups such that it is not
> appropriate to use one-way analysis of variance (perhaps after
> applying a transformation)?  If you are able to use one-way ANOVA, you
> can take advantage of a variety of methods for assessing the
> differences among the group means and dealing with the related
> multiple comparisons.
>
> David Hoaglin
>
> On Thu, Aug 29, 2013 at 2:22 AM, Célia Dechavanne <celia_dv@yahoo.fr> wrote:
> > Thank you for your help.
> > My first mail was not enough clear, sorry for that. The five groups are
> > small (minimum n=11 and maximum n=26). The KW test gives a significant
> > difference between the groups, now I would like to compare 2 by 2. But I
> > can't perform pairwise comparison, I would like to compare the shift between
> > the five groups. I hope is better clear now.
> > Thank you so much for the time spent to answer.
> > Best
> > Celia
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