perm.t.test: Permutation Student's t-test

In RVAideMemoire: Testing and Plotting Procedures for Biostatistics

Permutation Student's t-test

Description

Performs a permutation Student's t-test.

Usage

perm.t.test(x, ...)

## Default S3 method:
perm.t.test(x, y, paired = FALSE, ...)

## S3 method for class 'formula'
perm.t.test(formula, data, alternative = c("two.sided", "less", "greater"),
  paired = FALSE, nperm = 999, progress = TRUE, ...)

Arguments

x	a numeric vector of data values.
y	a numeric vector of data values.
paired	a logical indicating whether you want a paired t-test.
formula	a formula of the form a ~ b where a gives the data values and b a factor with 2 levels giving the corresponding groups.
data	an optional data frame containing the variables in the formula formula. By default the variables are taken from environment(formula).
alternative	a character string specifying the alternative hypothesis, must be one of "two.sided" (default), "greater" or "less".
nperm	number of permutations.
progress	logical indicating if the progress bar should be displayed.
...	further arguments to be passed to or from other methods.

Details

The function deals with the limitted floating point precision, which can bias calculation of p-values based on a discrete test statistic distribution.

Value

statistic	test statistics of the parametric test.
permutations	number of permutations.
p.value	p-value of the permutation test.
estimate	the estimated mean or difference in means depending on whether it was a paired or not paired test.
alternative	a character string describing the alternative hypothesis.
method	a character string indicating what type of t-test was performed.
data.name	a character string giving the name(s) of the data.
null.value	the specified hypothesized value of the mean difference, always 0.

Author(s)

Maxime HERVE <[e-mail]>

See Also

t.test

Examples

response <- c(rnorm(5),rnorm(5,2,1))
fact <- gl(2,5,labels=LETTERS[1:2])

# Not enough permutations here but faster to run

# Unpaired test
perm.t.test(response~fact,nperm=49)

# Paired test
perm.t.test(response~fact,paired=TRUE,nperm=49)

RVAideMemoire documentation built on Nov. 6, 2023, 5:07 p.m.