| boxcox(MASS) | R Documentation |
Computes and optionally plots profile log-likelihoods for the
parameter of the Box-Cox simple power transformation y^lambda.
boxcox(model, lambda, plotit, interp, eps, xlab, ylab, ...)
model |
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.
Default to true if a graphics device is currently open.
|
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.
data(trees)
boxcox(Volume ~ log(Height) + log(Girth), data = trees,
lambda = seq(-0.25, 0.25, length = 10))
data(quine)
boxcox(Days+1 ~ Eth*Sex*Age*Lrn, data = quine, singular.ok = TRUE,
lambda = seq(-0.05, 0.45, len = 20))