R help - Jun 2010 - Displaying "homogeneous groups" in aov post-hoc results ?

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



----------------Contact
Details:-------------------------------------------------------
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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
>
>
>
> ----------------Contact
> Details:-------------------------------------------------------
> Contact me: Tal.Galili at gmail.com | ?972-52-7275845
> Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) |
> www.r-statistics.com (English)
>
----------------------------------------------------------------------------------------------
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide
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>


-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/