# symbox

From car v1.0-18
by John Fox

##### Boxplots for transformations to symmetry

`symbox`

first transforms `x`

to each of a series
of selected powers, with each transformation standardized to mean 0 and
standard deviation 1. The results are then displayed side-by-side in boxplots, permiting
a visual assessment of which power makes the distribution reasonably symmetric.

- Keywords
- hplot

##### Usage

`symbox(x, powers=c(-1, -.5, 0, .5, 1), start=0)`

##### Arguments

- x
- a numeric vector.
- powers
- a vector of selected powers to which
`x`

is to be raised. A power of 0 is taken to mean $log(x)$. Negative powers are taken to mean $-x^p$, to preserve the order of the data. For meaningful comparison of powers, 1 s - start
- a constant to be added to
`x`

; after adding the start, all data values must be positive.

##### Value

- as returned by
`boxplot`

.

##### authors

Gregor Gorjanc, John Fox

##### References

Friendly, M. (2005)
*SAS System for Statistical Graphics, 2nd Edition.*
SAS Institute (In preparation).

##### See Also

##### Examples

```
data(Prestige)
symbox(Prestige$income)
```

*Documentation reproduced from package car, version 1.0-18, License: GPL version 2 or newer*

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