[R] Boxcox transformation / homogeneity of variances

From: Arnaud Dowkiw <arnaud.dowkiw_at_orleans.inra.fr>
Date: Wed 13 Jul 2005 - 18:18:58 EST


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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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Wed Jul 13 18:22:12 2005

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