[R] Looking for transformation to overcome heterogeneity of variances

[Paul Smith]

On 03 Aug 2006 15:45:10 +0200, Peter Dalgaard <p.dalgaard at biostat.ku.dk> wrote:
> > My data consists in 96 groups, each one with 10 observations. Levene's
> > test suggests that the variances are not equal, and therefore I have
> > tried to apply the classical transformations to have homocedasticity
> > in order to be able to use ANOVA. Unfortunately, no transformation
> > that I have used transforms my data into data with homocedasticity.
> > The histogram of variances is at
> >
> > http://phhs80.googlepages.com/hist1.png
> >
> > Is someone able to suggest to me a transformation to overcome the
> > problem of heterocedasticity?
>
> Not based on that information. Try the following instead:
>
> fit <- lm(y~g)
> par(mfrow=c(2,2)); plot(fit)

Thanks, Peter. By 'g', you mean

factor1* factor2*factor3*factor4

?

Paul