Example 1 (R-Code Script)
Two samples of Young walleye were drawn
from two different lakes and the fish were weighed. The data in g are:
R-Code and Results:
> X.1<-c(253,218,292,280,276,275)
> X.2<-c(216,291,256,270,277,285)
> sample<-c(rep(1,6),rep(2,6))
> w<-data.frame(c(X.1,X.2),sample)
> names(w)[1]<-'weight(g)'
> cbind(w[1:6,],w[7:12,])
weight(g)
sample weight(g) sample
1
253 1 216
2
2
218 1 291
2
3
292 1 256
2
4
280 1 270
2
5
276 1 277
2
6
275 1 285
2
> idx<-sort(w[,1],index.return=TRUE)
>
d<-rbind(weight=w[idx$ix,1],sample=w[idx$ix,2],
+ rank=1:12)
> dimnames(d)[[2]]<-rep('',12);d
weight 216 218 253 256 270 275 276 277 280 285 291
292
sample
2 1 1
2 2 1
1 2 1
2 2 1
rank
1 2 3
4 5 6
7 8 9
10 11 12
> rank.sum<-c(sum(d[3,d[2,]==1]),
+ sum(d[3,d[2,]==2]))
> rank.sum<-rbind(sample=c(1,2),
+ 'rank sum'=rank.sum)
> dimnames(rank.sum)[[2]]<-c('','');rank.sum
sample
1 2
rank sum 39 39
> wilcox.test(X.1,X.2)
Wilcoxon rank sum test
data: X.1
and X.2
W = 18, p-value = 1
alternative hypothesis: true location shift is not
equal to 0
>
