| vis.boxcox {TeachingDemos} | R Documentation |
Explore the Box-Cox family of distributions by plotting data transformed and untransformed and interactively choose values for lambda.
vis.boxcox(lambda = sample(c(-1,-0.5,0,1/3,1/2,1,2), 1),
hscale=1.5, vscale=1.5, wait=FALSE)
vis.boxcoxu(lambda = sample( c(-1,-0.5,0,1/3,1/2,1,2), 1),
y, xlab=deparse(substitute(y)),
hscale=1.5, vscale=1.5, wait=FALSE)
vis.boxcox.old(lambda = sample(c(-1, -0.5, 0, 1/3, 1/2, 1, 2), 1))
vis.boxcoxu.old(lambda = sample(c(-1, -0.5, 0, 1/3, 1/2, 1, 2), 1))
lambda |
The true value of lambda to use. |
y |
Optional data to use in the transform. |
xlab |
Label for x-axis. |
hscale |
The horizontal scale, passed to tkrplot. |
vscale |
The vertical scale, passed to tkrplot. |
wait |
Should R wait for the demo window to close. |
These functions will generate a sample of data and plot the
untrasformed data (left panels) and the transformed data (right
panels). Initially the value of lambda is 1 and the 2 sets of
plots will be identical.
You then adjust the transformation parameter lambda to see how
the right panels change.
The function vis.boxcox shows the effect of transforming the
y-variable in a simple linear regression.
The function vis.boxcoxu shows a single variable compared to
the normal distribution.
The old versions have no useful return value. If wait is FALSE
then they will return an invisible NULL, if wait is TRUE then
the return value will be a list with the final value of lamda,
the original data, and the transformed y (at the final lamda value).
Greg Snow greg.snow@imail.org
GEP Box; DR Cox. An Analysis of Transformations. Journal of the Royal Statitical Society. Series B, Vol. 26, No. 2 (1964) 211-252
bct, boxcox in package MASS
if(interactive()) {
vis.boxcoxu()
vis.boxcox()
}