Plot for Box-Cox Transformation Analysis
DESCRIPTION:
Displays a log-likelihood plot and/or lambda plot using the results of a Box-Cox transformation analysis.
USAGE: 
plot.boxcox(x, plot.type = "both", nlabs, conf = .95,...)
REQUIRED ARGUMENTS:
x:
object of class "boxcox", typically the output from performing a Box-Cox transformation analysis with boxcox.
OPTIONAL ARGUMENTS:
plot.type:
character string giving type of plot:"lambda" asks for a plot of t-values for all terms in the reduced model over lambda values of Box-Cox tranformations, "loglik" asks for a plot of log-likelihoods over lambda values; "both" produces both types of plot.
nlabs:
number of terms to be labelled in the lambda plot.
conf:
confidence level at which to draw confidence limits on the lambda plot.
...:
arguments to the function plot.
SIDE EFFECTS:
The plot or plots requested are drawn on the current graphics device.
DETAILS:
The log-likelihoods of different lambda values from a Box-Cox transformation analysis are plotted, showing which value of lambda maximizes the log-likelihood. A confidence interval for lambda is also plotted. The t-values for all terms in the reduced model associated with a Box-Cox transformation are plotted against lambda values. A two-sided confidence interval for significant effects is shown as well as the choice for the best lambda value.
REFERENCES:
Box, G.E.P. and D.R. Cox (1964) An analysis of transformations (with discussion). J. Royal Statist. Soc. Ser. B, 26:211-246

Box, G. E. P., W. G. Hunter, and J. S. Hunter (1978) Statistics for Experimenters, New York: Wiley.

Haaland, P. D. (1989) Experimental Design in Biotechnology, New York: Marcel Dekker.

SEE ALSO:
boxcox , fac.aov , lambda , loglik .
EXAMPLES: 
buffer.fac <- fac.aov(buffer.df)
buffer.bc <- boxcox(buffer.fac, ~pH*thimer+pH*gent)
plot(buffer.bc)