This function performs a Mann-Whitney-U-Test (or Wilcoxon rank sum test,
see wilcox.test and wilcox_test)
for x, for each group indicated by grp. If grp
has more than two categories, a comparison between each combination of
two groups is performed.
The function reports U, p and Z-values as well as effect size r
and group-rank-means.
Usage
mwu(x, grp, distribution = "asymptotic", weight.by = NULL)
Arguments
x
Numeric vector or variable.
grp
Grouping variable indicating the groups that should be used for comparison.
distribution
Indicates how the null distribution of the test statistic should be computed.
May be one of "exact", "approximate" or "asymptotic"
(default). See wilcox_test for details.
weight.by
Vector of weights that will be applied to weight all observations.
Must be a vector of same length as the input vector. Default is
NULL, so no weights are used.
Value
(Invisibly) returns a data frame with U, p and Z-values for each group-comparison
as well as effect-size r; additionally, group-labels and groups' n's are
also included.