> On 29 Apr 2016, at 23:54 , d...@stat.oregonstate.edu wrote:
>
> Hi,
>
> I noticed two seemingly equivalent call to boxplot will give different plots
> (in the way how the combined factor levels are arranged on the x-axis):
>
> x = factor(rep(c("a", "b", "c"), each=2));
> y = rep(factor(c("one", "two")), each=3);
> r = 3;
> n = r * 6;
> x = rep(x, 3);
> y = rep(y, 3);
> z = rnorm(n);
>
> par(mfrow=c(2,1));
>
> ## The following two seeming equivalent calls to boxplot give different
> results
> boxplot(z~x:y);
>
> f = x:y;
> boxplot(z~f);
>
> This is puzzling to me. Is this normal?
Normal, but a little odd. The root cause is the difference between x:y and
interaction(x,y), documented on the help page for the latter.
-pd
> Thanks!
>
> Best,
> Yanming
> [[alternative HTML version deleted]]
>
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--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd....@cbs.dk Priv: pda...@gmail.com
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