[R] kruskal wallis post hoc?

[Frank Harrell]

The Kruskal-Wallis test is a special case of the proportional odds ordinal
logistic model.  You can get any contrast you want by testing regression
coefficients.   In a couple of weeks the rms package's contrast function
will allow for individual confidence intervals of effects that together have
a 0.05 type I error, by using the multcomp package (called automatically
from contrast.rms).
Frank

Iasonas Lamprianou wrote
> 
> Thank you for the result, I will have a look at the link.
> 
>  
> Dr. Iasonas Lamprianou
> Department of Social and Political Sciences
> University of Cyprus
> 
> 
>>________________________________
>> From: Tal Galili <tal.galili@>
>>To: Iasonas Lamprianou <lamprianou@> 
>>Cc: "r-help@" <r-help@> 
>>Sent: Thursday, 12 January 2012, 10:48
>>Subject: Re: [R] kruskal wallis post hoc?
>> 
>>
>>Hi Iasonas ,
>>This is a stat question and not an R question.
>>But the general answer is that it could happen :)
>>
>>
>>The R question would have been if their is a Tukey HSD for kruskel.test,
the answer is yes:
>>http://stats.stackexchange.com/questions/17342/is-there-a-nonparametric-equivalent-of-tukey-hsd 
>>But if you didn't get any significant result from the pairwise comparison,
I would say that the post hoc correction wouldn't help you (it could be that
the reason for this significance is based on some weird contrast...)
>>
>>
>>Best,
>>Tal
>>
>>
>>
>>
>>
>>
>>
>>
>>----------------Contact
Details:-------------------------------------------------------
>>Contact me: Tal.Galili@ |  972-52-7275845
>>Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) |
www.r-statistics.com (English)
>>----------------------------------------------------------------------------------------------
>>
>>
>>
>>
>>
>>On Thu, Jan 12, 2012 at 8:35 AM, Iasonas Lamprianou <lamprianou@>
wrote:
>>
>>Dear all,
>>>
>>>I run a kruskal wallis test and found significant results. Then, I
conducted all pairwise comparisons and found no significant results. Could
anyone please give me a hint as to why this happens or redirect me towards a
specific web page where I can find more info? (I used alpha=5% and made no
bonferroni or other correction for the pairwise comparisons)
>>>Thank you
>>>
>>> 
>>>Dr. Iasonas Lamprianou
>>>Department of Social and Political Sciences
>>>University of Cyprus
>>>       [[alternative HTML version deleted]]
>>>
>>>
>>>______________________________________________
>>>R-help@ mailing list
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>>>PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>>>and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>>
>>
>>
> 	[[alternative HTML version deleted]]
> 
> 
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> 


-----
Frank Harrell
Department of Biostatistics, Vanderbilt University
--
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