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List:       r-help
Subject:    [R] wilcoxon-pratt signed rank  test in R -  drug-effiacy
From:       "Niels Steen Krogh" <nielssteenkrogh () hotmail ! com>
Date:       2003-12-01 10:51:59
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Hi.
I'm going to introduce the R-package for a group of medical doctors later 
this week and is a little confused about there use of a test named 
"willcoxon-pratt"  for testing if the clinical and biochemical markers has 
decreased significantly after the use of some drugs for a group of patients.

Looking into the R-functions I would in R recommand using a matched-pairs 
Wilcoxon test with a formula like:
wilcox.test(pre,post,alternative='greater',paired=T)

Looking deeper into the writings of Pratt I found some 1964-stuff "Pratt JW. 
Remarks on zeros and ties in the Wilcoxon signed rank procedures.  
J.Americ.Statistical Assoc. 1959; 54: 655-67. "

Do'es any of you know what is the wilcoxon-pratt test compared with the 
formula described above and how it should be implemented in R.

Thanks in advance

/Niels

Cand. Polit.
Niels Steen Krogh
Solsortvej 44
2000 F.

Tlf: 3888 8613

ZiteLab / EmpoweR youR data with R, Zope and SOAP


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