Kruskal-Wallis rank-sum test (non-parametric between-groups omnibus)

The non-parametric between-groups omnibus test: pools all observations, ranks them, and tests whether the rank totals differ across k >= 2 independent groups. It is the distribution-free counterpart of the one-way ANOVA (oneWayAnova) and, unlike it, makes no normality or equal-variance assumption. The tie-corrected statistic and its p-value reproduce base R stats::kruskal.test bit-for-bit (the H is accumulated in the same order) and scipy.stats.kruskal to machine precision.

Usage

kruskalTest(x, ...)

Arguments

x

Either a list of k >= 2 numeric group vectors, or the first group's numeric vector (with further groups passed through ...).

...

Additional numeric group vectors when x is a single vector.

Value

A list with statistic (the tie-corrected H), p_value, df (k - 1), k (number of groups) and n (total sample size).

See also

oneWayAnova, friedmanTest

Examples

kruskalTest(list(rnorm(20), rnorm(20, 1), rnorm(20, 2)))
#> $statistic
#> [1] 27.2118
#> 
#> $p_value
#> [1] 1.233196e-06
#> 
#> $df
#> [1] 2
#> 
#> $k
#> [1] 3
#> 
#> $n
#> [1] 60
#>