R help - Dec 2009 - anova

Dear friends, 

I have run an ANOVA using a linear variable as dependent and a nominal variable
with five groups as independent (factor). The F test is statistically
significant F(4, 431)=2.54, p=0.036.However, the multiple comparisons have shown
no difference between any two groups (no matter whether I used sheffe, tukeys,
lsd etc). What is the interpretation?

Thanks
Jason

This email list is about R, not introductory statistics. But the
answer to your question is: reject the 4 df hypothesis that the
population means of the 5 groups are all equal. Retain each single df
hypothesis about pairwise population mean differences.

-Ista

On Mon, Dec 28, 2009 at 6:02 AM, Iasonas Lamprianou
<lamprianou at yahoo.com> wrote:
> Dear friends,
>
> I have run an ANOVA using a linear variable as dependent and a nominal
variable with five groups as independent (factor). The F test is statistically
significant F(4, 431)=2.54, p=0.036.However, the multiple comparisons have shown
no difference between any two groups (no matter whether I used sheffe, tukeys,
lsd etc). What is the interpretation?
>
> Thanks
> Jason
>
>
>
>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org

You may need to look at some other contrasts than the pairwise.
For example,
3(x.bar_A + x.bar_B)  -  2(x.bar_C + x.bar_D + x.bar_E)