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st: Friedman tests


From   Ashley Harris <aharri@ucalgary.ca>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: Friedman tests
Date   Tue, 22 Mar 2005 10:34:59 -0700

Statalist, 

What I have nonparametric data for 3 groups, 1 dependent variable (ratio)
and 2 independent variables (technique and analysis type). The questions I
want to test are: does the technique matter with respect to the ratio
result?, does the analysis type matter with respect to the ratio result? is
there a difference between the groups? If so what are these differences?
However, there is the possibility of interactions, so I should test for that
as well. 

I think I want to use a Friedman test, but cannot seem to figure out how to
deal with interactions, and even more simplistically, I cannot seem to
replicate the results for the sample that is in the help file (pasted
below). Has any one had these problems too and is there a solution?

                          S t u d e n t
         --------------------------------------------
 T E S T      1    2    3    4    5    6    7    8
-----------------------------------------------------
 1            90   60   45   48   58   72   25   85
 2            62   81   92   76   70   75   95   72
 3            60   91   85   81   90   76   93   80

If you enter this as three variables, then you can just type in
    friedman varlist
and all is fine.  

The results from the above data are:
         Friedman =   2.8889
         Kendall =   0.1376
         p-value =   0.8951

Thanks for the help!
Ashley
A confused MSc student

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