pairwise.t.test {stats} | R Documentation |

## Pairwise t tests

### Description

Calculate pairwise comparisons between group levels with corrections for multiple testing

### Usage

```
pairwise.t.test(x, g, p.adjust.method = p.adjust.methods,
pool.sd = !paired, paired = FALSE,
alternative = c("two.sided", "less", "greater"),
...)
```

### Arguments

`x` |
response vector. |

`g` |
grouping vector or factor. |

`p.adjust.method` |
Method for adjusting p values (see |

`pool.sd` |
switch to allow/disallow the use of a pooled SD |

`paired` |
a logical indicating whether you want paired t-tests. |

`alternative` |
a character string specifying the alternative
hypothesis, must be one of |

`...` |
additional arguments to pass to |

### Details

The `pool.sd`

switch calculates a common SD for all
groups and uses that for all comparisons (this can be useful if some
groups are small). This method does not actually call `t.test`

,
so extra arguments are ignored. Pooling does not generalize to paired tests
so `pool.sd`

and `paired`

cannot both be `TRUE`

.

Only the lower triangle of the matrix of possible comparisons is being
calculated, so setting `alternative`

to anything other than
`"two.sided"`

requires that the levels of `g`

are ordered
sensibly.

### Value

Object of class `"pairwise.htest"`

### See Also

### Examples

```
attach(airquality)
Month <- factor(Month, labels = month.abb[5:9])
pairwise.t.test(Ozone, Month)
pairwise.t.test(Ozone, Month, p.adjust.method = "bonf")
pairwise.t.test(Ozone, Month, pool.sd = FALSE)
detach()
```

*stats*version 4.4.1 Index]