# leveneTest: Levene's Test In car: Companion to Applied Regression

## Description

Computes Levene's test for homogeneity of variance across groups.

## Usage

 ```1 2 3 4 5 6 7``` ```leveneTest(y, ...) ## S3 method for class 'formula' leveneTest(y, data, ...) ## S3 method for class 'lm' leveneTest(y, ...) ## Default S3 method: leveneTest(y, group, center=median, ...) ```

## Arguments

 `y` response variable for the default method, or a `lm` or `formula` object. If `y` is a linear-model object or a formula, the variables on the right-hand-side of the model must all be factors and must be completely crossed. `group` factor defining groups. `center` The name of a function to compute the center of each group; `mean` gives the original Levene's test; the default, `median`, provides a more robust test. `data` a data frame for evaluating the `formula`. `...` arguments to be passed down, e.g., `data` for the `formula` and `lm` methods; can also be used to pass arguments to the function given by `center` (e.g., `center=mean` and `trim=0.1` specify the 10% trimmed mean).

## Value

returns an object meant to be printed showing the results of the test.

## Note

adapted from a response posted by Brian Ripley to the r-help email list.

## Author(s)

John Fox [email protected]; original generic version contributed by Derek Ogle

## References

Fox, J. (2016) Applied Regression Analysis and Generalized Linear Models, Third Edition. Sage.

Fox, J. and Weisberg, S. (2019) An R Companion to Applied Regression, Third Edition, Sage.

## Examples

 ```1 2 3 4 5 6``` ```with(Moore, leveneTest(conformity, fcategory)) with(Moore, leveneTest(conformity, interaction(fcategory, partner.status))) leveneTest(conformity ~ fcategory*partner.status, data=Moore) leveneTest(lm(conformity ~ fcategory*partner.status, data=Moore)) leveneTest(conformity ~ fcategory*partner.status, data=Moore, center=mean) leveneTest(conformity ~ fcategory*partner.status, data=Moore, center=mean, trim=0.1) ```

### Example output

```Levene's Test for Homogeneity of Variance (center = median)
Df F value Pr(>F)
group  2   0.046 0.9551
42
Levene's Test for Homogeneity of Variance (center = median)
Df F value Pr(>F)
group  5  1.4694 0.2219
39
Levene's Test for Homogeneity of Variance (center = median)
Df F value Pr(>F)
group  5  1.4694 0.2219
39
Levene's Test for Homogeneity of Variance (center = median)
Df F value Pr(>F)
group  5  1.4694 0.2219
39
Levene's Test for Homogeneity of Variance (center = mean)
Df F value Pr(>F)
group  5  1.7915 0.1373
39
Levene's Test for Homogeneity of Variance (center = mean: 0.1)
Df F value Pr(>F)
group  5  1.7962 0.1363
39
```

car documentation built on May 27, 2019, 5:02 p.m.