[R] SpreadLevelPlot for more than one factor
ashimkapoor at gmail.com
Tue Jan 9 16:18:34 CET 2018
Many thanks for your reply.
I have a query.
I have a whole set of distributions which should be made normal /
homoscedastic. Take for instance the warpbreaks data set.
We have the following boxplots for the warpbreaks dataset:
a. boxplot(breaks ~ wool)
b. boxplot(breaks ~ tension)
c. boxplot(breaks ~ interaction(wool,tension))
d. boxplot(breaks ~ wool @ each level of tension)
e. boxplot(breaks ~ tension @ each level of wool)
Now should we not be making a-e normal and homoscedastic? Should we not
make a giant collection of boxplots from a-e and use the SpreadLevelPlot on
this entire collection?
A second query : (d) and (e) are the distribution of the simple effects of
factor wool and tension @ each level of the other. Is that correct? Are
(a) and (b) the distribution of the main effect of wool and tension? Please
On Sun, Jan 7, 2018 at 8:05 PM, Fox, John <jfox at mcmaster.ca> wrote:
> Dear Ashim,
> Try spreadLevelPlot(breaks ~ interaction(tension, wool), data=warpbreaks) .
> I hope this helps,
> John Fox, Professor Emeritus
> McMaster University
> Hamilton, Ontario, Canada
> Web: socialsciences.mcmaster.ca/jfox/
> > -----Original Message-----
> > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Ashim
> > Kapoor
> > Sent: Sunday, January 7, 2018 12:08 AM
> > To: r-help at r-project.org
> > Subject: [R] SpreadLevelPlot for more than one factor
> > Dear All,
> > I want a transformation which will make the spread of the response at
> > combinations of 2 factors the same.
> > See for example :
> > boxplot(breaks ~ tension * wool, warpbreaks)
> > The closest I can do is :
> > spreadLevelPlot(breaks ~tension , warpbreaks) spreadLevelPlot(breaks ~
> wool ,
> > warpbreaks)
> > I want to do :
> > spreadLevelPlot(breaks ~tension * wool, warpbreaks)
> > But I get :
> > > spreadLevelPlot(breaks ~tension * wool , warpbreaks)
> > Error in spreadLevelPlot.formula(breaks ~ tension * wool, warpbreaks) :
> > right-hand side of model has more than one variable
> > What is the corresponding appropriate function for 2 factors ?
> > Many thanks,
> > Ashim
> > [[alternative HTML version deleted]]
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