| boxcox {MASS} | R Documentation |
Computes and optionally plots profile log-likelihoods for the parameter of the Box-Cox power transformation.
boxcox(object, ...)
## Default S3 method:
boxcox(object, lambda = seq(-2, 2, 1/10), plotit = TRUE,
interp, eps = 1/50, xlab = expression(lambda),
ylab = "log-Likelihood", ...)
## S3 method for class 'formula':
boxcox(object, lambda = seq(-2, 2, 1/10), plotit = TRUE,
interp, eps = 1/50, xlab = expression(lambda),
ylab = "log-Likelihood", ...)
## S3 method for class 'lm':
boxcox(object, lambda = seq(-2, 2, 1/10), plotit = TRUE,
interp, eps = 1/50, xlab = expression(lambda),
ylab = "log-Likelihood", ...)
object |
a formula or fitted model object. Currently only lm and
aov objects are handled.
|
lambda |
vector of values of lambda – default (-2, 2) in steps of 0.1.
|
plotit |
logical which controls whether the result should be plotted. |
interp |
logical which controls whether spline interpolation is used.
Default to TRUE if plotting with lambda of length less than 100.
|
eps |
Tolerance for lambda = 0; defaults to 0.02.
|
xlab |
defaults to "lambda".
|
ylab |
defaults to "log-Likelihood".
|
... |
additional parameters to be used in the model fitting. |
A list of the lambda vector and the computed profile
log-likelihood vector, invisibly if the result is plotted.
If plotit = TRUE plots loglik vs lambda and indicates a 95%
confidence interval about the maximum observed value of lambda. If
interp = TRUE, spline interpolation is used to give a smoother plot.
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.
data(trees)
boxcox(Volume ~ log(Height) + log(Girth), data = trees,
lambda = seq(-0.25, 0.25, length = 10))
boxcox(Days+1 ~ Eth*Sex*Age*Lrn, data = quine,
lambda = seq(-0.05, 0.45, len = 20))