From ATurpin@discoveriesinsight.org  Sat Aug  7 01:09:31 1999
From: ATurpin@discoveriesinsight.org (ATurpin@discoveriesinsight.org)
Date: Sat, 7 Aug 1999 02:09:31 +0200 (MET DST)
Subject: bug ? wilcox() (PR#243)
Message-ID: <199908070009.CAA02388@pubhealth.ku.dk>

> Hi,
> 
> I am getting a strange result from the wilcox function in the code below.
> This code has worked for many other wilcox's, but not this particular one.
> The p-value printed should be much higher (consistent with the p-value
> for the t-test).
> 
> I am using R Version 0.64.2 under Debian Linux.
> 
> I hope it is not me being stupid...
> 
> Regards,
> 
> Andrew Turpin
> aturpin@discoveriesinsight.org
> 
> --------------------------------------------------------------------------
> ----
> 
> library(ctest)
> x <- vector(length=50)
> y <- vector(length=50)
> x <- c(0.624200,0.252100
> ,0.404500
> ,0.465000
> ,0.033500
> ,0.565500
> ,0.316000
> ,0.469800
> ,0.590200
> ,0.420200
> ,0.609800
> ,0.577800
> ,0.854200
> ,0.284800
> ,0.243600
> ,0.596100
> ,0.213200
> ,0.369800
> ,0.281400
> ,0.754500
> ,0.135200
> ,0.041900
> ,0.640900
> ,0.547000
> ,0.214300
> ,0.212000
> ,0.325200
> ,0.400700
> ,0.115400
> ,0.248800
> ,0.211500
> ,0.540200
> ,0.282100
> ,0.131700
> ,0.757500
> ,0.136500
> ,0.391500
> ,0.293500
> ,0.275400
> ,0.048700
> ,0.308400
> ,0.140900
> ,0.624100
> ,0.042600
> ,0.158100
> ,0.631300
> ,0.279200
> ,0.623100
> ,0.042600
> ,0.477200
> )
> y <- c(0.606500,0.252100
> ,0.404500
> ,0.465000
> ,0.033500
> ,0.565500
> ,0.316000
> ,0.469800
> ,0.591700
> ,0.420200
> ,0.608700
> ,0.577800
> ,0.854200
> ,0.284800
> ,0.244700
> ,0.596100
> ,0.213200
> ,0.369800
> ,0.281400
> ,0.754500
> ,0.135200
> ,0.041900
> ,0.640900
> ,0.683500
> ,0.214300
> ,0.192100
> ,0.304800
> ,0.400700
> ,0.115400
> ,0.248800
> ,0.211500
> ,0.540200
> ,0.282100
> ,0.131700
> ,0.757500
> ,0.137200
> ,0.391500
> ,0.293500
> ,0.275400
> ,0.048700
> ,0.308400
> ,0.140900
> ,0.624100
> ,0.042600
> ,0.158100
> ,0.631300
> ,0.282900
> ,0.620100
> ,0.030800
> ,0.471700
> )
>         #
>         # some functions for formatting output
>         #
>      f    <- function (x) { formatC(x,digits=4,width=10,format="f") }
>      mydiff<-function (x,y) {
> formatC((y-x)/y*100,digits=2,width=10,format="f")}
>      line <- function (d,x,y) { cat(d,f(x),f(y),mydiff(x,y),"\n")}
> 
>         #
>         # print basic stats
>         #
>      line("n           ",length(x),length(y))
>      line("Mean        ",mean(x),mean(y))
>      line("Median      ",median(x),median(y))
>      line("Var         ",var(x),var(y))
> 
>      cat("\n")
> 
>         #
>         # Perform basic tests
>         #
>      w  <- wilcox.test(x,y,paired=TRUE)
>      t  <- t.test(x,y,paired=TRUE)
> 
>      cat("t-test   p =", f(t$p.value),
> ifelse(t$p.value<0.05,"(Significant)","(Not significant)"), "\n")
>      cat("Wilcoxon p =",
> f(w$p.value),ifelse(w$p.value<0.05,"(Significant)","(Not significant)"),
> "\n")
> 

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bug ? wilcox() (PR#243)
ATurpin@discoveriesinsight.org