pairwiseMedianMatrix {rcompanion}

Pairwise Mood's median tests with matrix output

Description

Conducts pairwise Mood's median tests across groups.

Usage

pairwiseMedianMatrix(
  formula = NULL,
  data = NULL,
  x = NULL,
  g = NULL,
  digits = 4,
  method = "fdr",
  ...
)

Arguments

formula

A formula indicating the measurement variable and the grouping variable. e.g. y ~ group.

data

The data frame to use.

x

The response variable as a vector.

g

The grouping variable as a vector.

digits

The number of significant digits to round output.

method

The p-value adjustment method to use for multiple tests. See stats::p.adjust.

...

Additional arguments passed to coin::median_test.

Details

The input should include either formula and data; or x, and g.

Mood's median test compares medians among two or more groups. See https://rcompanion.org/handbook/F_09.html for futher discussion of this test.

The pairwiseMedianMatrix function can be used as a post-hoc method following an omnibus Mood's median test. It passes the data for pairwise groups to coin::median_test.

The matrix output can be converted to a compact letter display, as in the example.

Value

A list consisting of: a matrix of p-values; the p-value adjustment method; a matrix of adjusted p-values.

Note

The parsing of the formula is simplistic. The first variable on the left side is used as the measurement variable. The first variable on the right side is used for the grouping variable.

Author(s)

Salvatore Mangiafico, [e-mail]

References

https://rcompanion.org/handbook/F_09.html

See Also

pairwiseMedianTest

Examples

data(PoohPiglet)
PoohPiglet$Speaker = factor(PoohPiglet$Speaker,
                          levels = c("Pooh", "Tigger", "Piglet"))
PT = pairwiseMedianMatrix(Likert ~ Speaker,
                          data   = PoohPiglet,
                          exact  = NULL,
                          method = "fdr")$Adjusted
PT                           
library(multcompView)
multcompLetters(PT,
                compare="<",
                threshold=0.05,
                Letters=letters)