[R] Displaying "homogeneous groups" in aov post-hoc results ?

[Hadley Wickham]

Try multcompView

Hadley

On Sat, Jun 12, 2010 at 8:42 AM, Tal Galili <tal.galili at gmail.com> wrote:
> Hello dear R-help mailing list,
>
> A friend of mine teaches a regression and experimental design course and
> asked me the following question.
>
> She is trying to find a way to display the "homogeneous groups" (after
> performing tukey test on an aov object).
>
> here's an example for what she means by "homogeneous groups":
> She did one way anova and got these results for tukey test:
>> TukeyHSD(hci_anova)
>  Tukey multiple comparisons of means
>    95% family-wise confidence level
> Fit: aov(formula = time ~ interface, data = hci)
> $interface
>         diff          lwr         upr       p adj
> B-A  -23.75   -73.732836    26.23284   0.4165355
> C-A    31.25   -18.732836    81.23284   0.2415169
> C-B    55.00     5.017164   104.98284   0.0323006
>
> now, she says, since she can see that the only significant difference is
> between C and B treatments, then B and A are on the same group (no
> significant difference),  C and A are on the same group, but B anc C are not
> in the same group. so we should have two groups:
> A and B
> A and C
>
> Apparently SPSS output gives the homogeneous subsets.
>
>
> Do you know of a way in R to do that?
> Also, since I am unfamiliar with this presentation, do you believe it is
> useful/has value?
>
>
> Thanks,
> Tal
>
>
>
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-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/