posthoc_anova: !! Post-hoc tests for ANOVA and Welch ANOVA
In GegznaV/BioStat: Routines for Basic (Bio)Statistics

Description Usage Arguments Details Value Note Author(s) See Also Examples

Games-Howell, Tukey HSD and other post-hoc tests for ANOVA and Welch ANOVA. Either Games-Howell test or Tukey honestly significant difference (HSD) post-hoc tests for one-way analysis of variance (ANOVA).

posthoc_anova(
  y,
  group = NULL,
  method = c("Games-Howell", "Tukey"),
  conf_level = 0.95,
  digits = 3,
  digits_p = 3,
  p_adjust = "none",
  format_pvalue = TRUE,
  data = NULL,
  ...
)

## S3 method for class 'formula'
posthoc_anova(
  y,
  group = NULL,
  method = c("Games-Howell", "Tukey"),
  conf_level = 0.95,
  digits = 3,
  digits_p = 3,
  p_adjust = "none",
  format_pvalue = TRUE,
  data = NULL,
  ...,
  sep = " | "
)

## Default S3 method:
posthoc_anova(
  y,
  group = NULL,
  method = c("Games-Howell", "Tukey"),
  conf_level = 0.95,
  digits = 3,
  digits_p = 3,
  p_adjust = "none",
  format_pvalue = TRUE,
  data = NULL,
  ...
)

## S3 method for class 'posthoc_anova'
print(
  x,
  digits = x$input$digits,
  digits_p = x$input$digits_p,
  digits_param = 2,
  ...
)

## S3 method for class 'posthoc_anova'
plot(
  x,
  ...,
  zero_line_color = "grey",
  add_p = TRUE,
  p_size = 1,
  p_color = "blue",
  p_pos_adj = 0.22,
  flip_xy = TRUE
)

`y`	(numeric\|formula) Either a numeric vector or formula.
`group`	(factor) a vector that either is a factor or can be converted into one. If `y` is a formula, `group` is ignored.
`method`	(`"games-howell"`\|`"tukey"`) Name of post-hoc tests to conduct. Valid values are "tukey" and "games-howell".
`conf_level`	(number) Confidence level (equals to `1 - alpha`, where alpha is significanve level). Number from 0 to 1. Default is 0.95.
`digits`	(integer) The number of digits to round data related numbers to.
`digits_p`	(integer) The number of digits to round p values to. Must be 2, 3 or more.
`p_adjust`	Any valid `stats::p.adjust()` method.
`format_pvalue`	(does not work yet) Whether to format the p values according to APA standards (i.e. replace all values lower than .001 with '<.001'). This only applies to the printing of the object, not to the way the p values are stored in the object.
`data`	(data frame) a data frame with data to be used in combination with formula.
`...`	Further arguments to methods.
`sep`	(character) A string with a symbol to separate group names if several grouping variables are used.
`x`	object to print.
`zero_line_color`	(character) Color for line indicating zero differences.
`add_p`	(logical) Flag if p values should be added.
`p_size`	(numeric) Font size to p-values-related text.
`p_color`	(character) Color for p values.
`p_pos_adj`	(numeric) Factor for p value position correction
`flip_xy`	(logical) Flag if x and y axes should be swapped.

The main part of the function code and descriptions were imported from posthocTGH() in package userfriendlyscience.

A list of three elements:

`input`	List with input arguments
`output`	List with post-hoc test results

Options that carry out Games-Howell and Tukey HSD analyses are based on code of function posthocTGH() in package userfriendlyscience (version 0.7.0).

Gjalt-Jorn Peters (Open University of the Netherlands)
Jeff Bagget (University of Wisconsin - La Crosse)
Vilmantas Gegzna

library(biostat)

# Compute post-hoc statistics using the Games-Howell method
posthoc_anova(weight ~ Diet, data = ChickWeight, method = "Games-Howell")

# Compute post-hoc statistics using the Tukey method
posthoc_anova(weight ~ Diet, data = ChickWeight, method = "Tukey")