R: Rotating Rats

rotarod {coin} | R Documentation

## Rotating Rats

### Description

The endurance time of 24 rats in two groups on a rotating cylinder.

### Usage

    rotarod

### Format

A data frame with 24 observations on 2 variables.

`time`

  endurance time (seconds).

`group`

  a factor with levels `"control"` and `"treatment"`.

### Details

The rats were randomly assigned to receive a fixed oral dose of a centrally acting muscle relaxant (`"treatment"`) or a saline solvent (`"control"`). The animals were placed on a rotating cylinder and the endurance time of each rat, i.e., the length of time each rat remained on the cylinder, was measured up to a maximum of 300 seconds.

This dataset is the basis of a comparison of 11 different software implementations of the Wilcoxon-Mann-Whitney test presented in Bergmann, Ludbrook and Spooren (2000).

### Note

The empirical variance in the control group is 0 and the group medians are identical. The exact conditional p-values are 0.0373 (two-sided) and 0.0186 (one-sided). The asymptotic two-sided p-value (corrected for ties) is 0.0147.

### Source

Bergmann, R., Ludbrook, J. and Spooren, W. P. J. M. (2000). Different outcomes of the Wilcoxon-Mann-Whitney test from different statistics packages. The American Statistician 54(1), 72–77.

### Examples

    ## One-sided exact Wilcoxon-Mann-Whitney test (p = 0.0186)
    wilcox_test(time ~ group, data = rotarod, distribution = "exact",
                alternative = "greater")

    ## Two-sided exact Wilcoxon-Mann-Whitney test (p = 0.0373)
    wilcox_test(time ~ group, data = rotarod, distribution = "exact")

    ## Two-sided asymptotic Wilcoxon-Mann-Whitney test (p = 0.0147)
    wilcox_test(time ~ group, data = rotarod)

[Package coin version 1.1-3 Index]