# perm.test: Permutation t-test In broman: Karl Broman's R Code

 perm.test R Documentation

## Permutation t-test

### Description

Calculates a p-value for a t-test via permutations.

### Usage

```perm.test(x, y, n.perm = NULL, var.equal = TRUE, pval = TRUE)
```

### Arguments

 `x` A numeric vector. `y` A second numeric vector. `n.perm` Number of permutations to perform. If NULL, all possible permutations are considered, and an exact p-value is calculated. `var.equal` A logical variable indicating whether to treat the two population variances as being equal. `pval` If TRUE, return just the p-value. If FALSE, return the actual permutation results (with the observed statistic as an attribute, `"tobs"`).

### Details

This calls the function `stats::t.test()` to calculate a t-statistic comparing the vectors `x` and `y`. Permutations are perfomed to give an exact or approximate conditional p-value.

### Value

If `pval=TRUE`, the output is a single number: the P-value testing for a difference in the distributions of the populations from which `x` and `y` were drawn. If `pval=FALSE`, the output is a vector of the t statistics from the permutations. An attributed `"tobs"` contains the t statistic with the observed data.

`stats::t.test()`, `paired.perm.test()`

### Examples

```x <- c(43.3, 57.1, 35.0, 50.0, 38.2, 61.2)
y <- c(51.9, 95.1, 90.0, 49.7, 101.5, 74.1)
perm.test(x,y)

```

broman documentation built on July 8, 2022, 5:07 p.m.