```
with(sleep, compare.2.vectors(extra[group == 1], extra[group == 2]))
# gives:
## $parametric
## test test.statistic test.value test.df p
## 1 t t -1.861 18.00 0.07919
## 2 Welch t -1.861 17.78 0.07939
##
## $nonparametric
## test test.statistic test.value test.df p
## 1 stats::Wilcoxon W 25.500 NA 0.06933
## 2 permutation Z -1.751 NA 0.08154
## 3 coin::Wilcoxon Z -1.854 NA 0.06487
## 4 median Z -1.744 NA 0.17867
# compare with:
with(sleep, compare.2.vectors(extra[group == 1], extra[group == 2],
alternative = "less"))
with(sleep, compare.2.vectors(extra[group == 1], extra[group == 2],
alternative = "greater"))
# doesn't make much sense as the data is not paired, but whatever:
with(sleep, compare.2.vectors(extra[group == 1], extra[group == 2],
paired = TRUE))
# from ?t.test:
compare.2.vectors(1:10,y=c(7:20, 200))
```

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