symbox

0th

Percentile

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, ...)
## S3 method for class 'formula':
symbox(formula, data=NULL, subset, na.action=NULL, ylab,  ...)
## S3 method for class 'default':
symbox(x, powers = c(-1, -0.5, 0, 0.5, 1), start=0, 
	trans=bcPower, xlab="Powers", ylab, ...)
Arguments
x
a numeric vector.
formula
a one-sided formula specifying a single numeric variable.
data, subset, na.action
as for statistical modeling functions (see, e.g., lm).
xlab, ylab
axis labels; if ylab is missing, a label will be supplied.
powers
a vector of selected powers to which x is to be raised. For meaningful comparison of powers, 1 should be included in the vector of powers.
start
a constant to be added to x.
trans
a transformation function whose first argument is a numeric vector and whose second argument is a transformation parameter, given by the powers argument; the default is bcPower, and
...
arguments to be passed down.
Value

  • as returned by boxplot.

References

Fox, J. and Weisberg, S. (2011) An R Companion to Applied Regression, Second Edition. Sage.

See Also

boxplot, boxcox, bcPower, yjPower

Aliases
  • symbox
  • symbox.formula
  • symbox.default
Examples
symbox(~ income, data=Prestige)
Documentation reproduced from package car, version 2.0-11, License: GPL (>= 2)

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