R语言教程之群体差异的非参数检验Nonparametric Tests of Group Differences

R提供执行Mann-Whitney U，Wilcoxon签名排名，Kruskal Wallis和Friedman测试的功能。

# independent 2-group Mann-Whitney U Test wilcox.test(y~A) # where y is numeric and A is A binary factor

# independent 2-group Mann-Whitney U Test wilcox.test(y,x) # where y and x are numeric

# dependent 2-group Wilcoxon Signed Rank Test wilcox.test(y1,y2,paired=TRUE) # where y1 and y2 are numeric

# Kruskal Wallis Test One Way Anova by Ranks kruskal.test(y~A) # where y1 is numeric and A is a factor

# Randomized Block Design - Friedman Test friedman.test(y~A|B) # where y are the data values, A is a grouping factor # and B is a blocking factor

对于wilcox.test，您可以使用alternative =“less”或alternative =“greater”选项来指定单尾测试。

参数和重新取样的替代品是可用的。

软件包pgirmess提供了非参数多重比较。（注意：该软件包已被撤销，但仍可在CRAN档案中找到。）

library(npmc) npmc(x) # where x is a data frame containing variable 'var' # (response variable) and 'class' (grouping variable)

可视化结果

使用箱形图或密度图来显示组的差异。

这个交互式示例允许您使用R练习Wilcoxon签名排名测试。