Hello David,
I wanted to thank you for pointing to this code for performing posthoc
friedman test. I just used this example to create a function to perform this
test (and also added some illustrative flexible plots to the mix), here:
http://www.r-statistics.com/2010/02/post-hoc-analysis-for-friedmans-test-r-code/

Best,
Tal




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On Mon, Sep 21, 2009 at 3:35 AM, David Winsemius <dwinsemius@comcast.net>wrote:

>
> On Sep 20, 2009, at 9:05 PM, jon@terraspark.com wrote:
>
>  Hi there all,
>>
>> This is my first post to the list and I'll first say a few things:
>> - R is great!
>> - The archives of this list have helped me solve all of my
>> problems/questions so far
>> - I only know enough statistics "to be dangerous"
>>
>> I'm looking for a way to do post-hoc tests for the Friedman test. I have a
>> dataset from a within-subjects design with 5 conditions where some of the
>> dependent variables are ordinal, resulting from (summed) likert-scaled
>> questionnaire data.
>>
>> From what I've read, I could use a wilcox.test on pairs of conditions and
>> adjust the p level, but is there something in R that does a better
>> job/automates this.
>>
>> I've seen references to the npmc package but that doesn't seem to do what
>> I'm looking for, because it only accepts a data frame with two columns -
>> i.e. there's no way to specify grouping/subject identifiers.
>>
>> Thanks,
>>
>
> There is a worked example in the coin package for using a permutation test
> to examine differences after a Friedman test. The authors, Hothorn , Hornik
> , van de Wiel, and Zeileis, call this method the
> Wilcoxon-Nemenyi-McDonald-Thompson test and cite: Hollander & Wolfe (1999),
> page 295
>
>
> http://finzi.psych.upenn.edu/R/library/coin/html/SymmetryTests.html
>
> --
> David Winsemius, MD
> Heritage Laboratories
> West Hartford, CT
>
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>

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