# C.test: Cochran's C test of homogeneity of variances In GAD: GAD: Analysis of variance from general principles

## Description

Performs a Cochran's test of the null hypothesis that the largest variance in several sampled variances are the same.

## Usage

 `1` ```C.test(object) ```

## Arguments

 `object` An object of class lm, containing the specified design.

## Details

The test statistic is a ratio that relates the largest variance to the sum of the sampled variances.

## Value

A list of class htest containing the following components:

 `statistic` Cochran's C test statistic `p-value` The p-value of the test `alternative` A character string describing the alternative hypothesis `method` The character string Cochran test of homogeneity of variances `data.name` A character string giving the name of the lm object `estimate` Sample estimates of variances

## Author(s)

Leonardo Sandrini-Neto (leonardosandrini@gmail.com)

`gad`

## Examples

 ```1 2 3 4 5 6``` ``` library(GAD) data(rohlf95) cg <- as.fixed(rohlf95\$cages) mq <- as.random(rohlf95\$mosquito) model <- lm(wing ~ cg + mq%in%cg, data = rohlf95) C.test(model) ```

### Example output

```Loading required package: matrixStats
R.methodsS3 v1.7.1 (2016-02-15) successfully loaded. See ?R.methodsS3 for help.

Cochran test of homogeneity of variances

data:  model
C = 0.30762, n = 2, k = 12, p-value = 0.5899
alternative hypothesis: Group cage1.m2 has outlying variance
sample estimates:
cage1.m1 cage1.m2 cage1.m3 cage1.m4 cage2.m1 cage2.m2 cage2.m3 cage2.m4
0.500    4.805    0.080    1.620    0.000    1.125    0.980    2.000
cage3.m1 cage3.m2 cage3.m3 cage3.m4
0.405    0.980    0.245    2.880
```

GAD documentation built on May 2, 2019, 3:01 a.m.