[R] Boxcox transformation / homogeneity of variances

[Arnaud Dowkiw]

Dear r-helpers,

Prior to analysis of variance, I ran the Boxcox function (MASS library) to 
find the best power transformation of my data. However, reading the Boxcox 
help file, I cannot figure out if this function (through its associated 
log-likelihood function) corrects for * normality only * or if it also 
induces * homogeneity of variances *. I found in Biometry (Sokal and Rohlf, 
p. 419) that the box-cox transformation can be extended to induce 
homogenity of variances in conjunction with Bartlett's test of homogeneity 
of variances. Does the Boxcox function implemented in R refer to this 
extension ?
Thanks a lot,


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Arnaud DOWKIW
INRA
Forest Research
Avenue de la Pomme de Pin
BP 20619 ARDON
45166 OLIVET CEDEX
FRANCE
Tel. + 33 2 38 41 78 00
Fax. + 33 2 38 41 48 09
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