box.cox

Dear Tal and Rosario,

The bcPower() function in the car package computes Box-Cox power
transformations; boxcox() in the MASS package estimates the response
transformation parameter for the Box-Cox regression model (actually the
profile log-likelihood for a range of variables of the parameter). The two
functions do different things. The boxCox() function in the car package is a
slight generalization of boxcox(), allowing for other families of
transformations than the Box-Cox powers; the powerTransform() function in
the car package is more general still, in that it will handle multivariate
transformations, both conditional (like the Box-Cox regression model) and
unconditional.

bcPower() was named box.cox() in earlier versions of the car package,
associated with the first edition of the R [and S-PLUS] Companion to Applied
Regression. In newer versions of the package, associated with the second
edition of the book, written with Sandy Weisberg, this and other functions
have been renamed to remove periods in function names. The older,
"deprecated," names of the functions are retained as a courtesy to readers
of the first edition.

Best,
 John

--------------------------------
John Fox
Senator William McMaster
  Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox

box.cox

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