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
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