# hovBF: Homogeneity of Variance: Brown-Forsyth method In HH: Statistical Analysis and Data Display: Heiberger and Holland

## Description

Homogeneity of Variance: Brown–Forsyth method

## Usage

 ```1 2 3``` ```hovBF(x, data=NULL, ..., na.rm = TRUE) hovplotBF(x, data, ..., na.rm = TRUE, main = "Brown-Forsyth Homogeneity of Variance", plotmath = TRUE) ```

## Arguments

 `x` Model formula with one response variable and one factor. `data` `data.frame` `...` Other arguments. `hovplotBF` sends them on to the panel function. `hovBF` ignores them. `na.rm` A logical value indicating whether 'NA' values should be stripped before the computation proceeds. See `median`. `main` `main` title for the plot. `plotmath` Logical. When `TRUE` (the default) the strip labels use `plotmath`. When `FALSE` the strip labels use ASCII.

## Value

`hovplotBF` returns a three-panel `trellis` object. `hovBF` returns an `htest` object.

## Author(s)

Richard M. Heiberger <rmh@temple.edu>

## References

Brown, M.~B. and Forsyth, A.~B. (1974). “Robust tests for equality of variances.” Journal of the American Statistical Association, 69:364–367.

## Examples

 ```1 2 3 4 5``` ```data(batch) batch1.aov <- aov(Calcium ~ Batch, data=batch) anova(batch1.aov) hovBF(Calcium ~ Batch, data=batch) hovplotBF(Calcium ~ Batch, data=batch) ```

### Example output

```Loading required package: lattice

Attaching package: 'TH.data'

The following object is masked from 'package:MASS':

geyser

Analysis of Variance Table

Response: Calcium
Df   Sum Sq  Mean Sq F value   Pr(>F)
Batch      4 0.096976 0.024244  5.5352 0.003626 **
Residuals 20 0.087600 0.004380
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

hov: Brown-Forsyth

data:  Calcium
F = 0.032193, df:Batch = 4, df:Residuals = 20, p-value = 0.9978
alternative hypothesis: variances are not identical

Warning messages:
1: In formals(fun) : argument is not a function
2: In formals(fun) : argument is not a function
```

HH documentation built on Nov. 28, 2020, 9:06 a.m.