| logtrans {MASS} | R Documentation |
Find and optionally plot the marginal (profile) likelihood for alpha
for a transformation model of the form log(y + alpha) ~ x1 + x2 + ....
logtrans(object, ...)
## Default S3 method:
logtrans(object, ..., alpha = seq(0.5, 6, by = 0.25) - min(y),
plotit = TRUE, interp =, xlab = "alpha", ylab = "log Likelihood")
## S3 method for class 'formula':
logtrans(object, data, ...)
## S3 method for class 'lm':
logtrans(object, ...)
object |
Fitted linear model object, or formula defining the untransformed
model that is y ~ x1 + x2 + .... The function is generic.
|
... |
If object is a formula, this argument may specify a data frame
as for lm.
|
alpha |
Set of values for the transformation parameter, alpha. |
plotit |
Should plotting be done? |
interp |
Should the marginal log-likelihood be interpolated with a spline
approximation? (Default is TRUE if plotting is to be done and
the number of real points is less than 100.)
|
xlab |
as for plot.
|
ylab |
as for plot.
|
data |
optional data argument for lm fit.
|
List with components x (for alpha) and y (for the marginal
log-likelihood values).
A plot of the marginal log-likelihood is produced, if requested, together with an approximate mle and 95% confidence interval.
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.
logtrans(Days ~ Age*Sex*Eth*Lrn, data = quine,
alpha = seq(0.75, 6.5, len=20))