[S] Box-Cox transformation in anova

Matthieu Lesnoff (lesnoff@hpbaill.cirad.fr)
Fri, 09 Oct 1998 09:40:33 +0200


Dear all,

I have a quantitative dependent variable "y" and two qualitative factors
"A" and "B". I did a typical anova (with lm function) with the model y ~ A
+ B + A:B, and I observed variance heterogeneity in the residuals.

I would like to transform the dependent variable with the Box-Cox
transformation to stabilize the variance in the studied design (that is I
want to find the MV estimator of lamda in the transformed y^lambda).

Is there a simple way to do this with Splus ?

Many thanks
Matthieu LESNOFF
CIRAD-EMVT (Département Elevage et Medecine Vétérinaire Tropicale)
Programme Productions Animales
Campus de Baillarguet
BP 5035
34032 Montpellier Cedex 1 (France)
email : matthieu.lesnoff@cirad.fr
tel : 04 67 59 37 70
fax : 04 67 59 38 25
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