Re: [Freesurfer] Group effect Contrast for 6 groups

[cody samth]

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Great thanks.

On Fri, Oct 18, 2019, 10:09 AM Greve, Douglas N.,Ph.D., <
dgr...@mgh.harvard.edu> wrote:

> Yes, that is correct. It is testing the null hypothesis A=B=C=D=E=F. That
> hypothesis will be rejected if A is different from B-F, which is what you
> are testing. The other contrasts are redundant (and would cause an error if
> you added them to the contrast matrix)z
>
> On 10/16/19 12:03 PM, cody samth wrote:
>
> External Email - Use Caution
> Hi,
>
> I'm designing an analysis that will have 6 groups (two factors/three
> levels). I was wondering if I could get some input regarding my contrast
> for the group effect. Based on the group effect contrast under the FSGD
> examples for 3 groups I've written a five line contrast file that compares
> group 1 against the other 5 groups.
>
> 1-1 0 0 0 0
> 1 0 -1 0 0 0
> 1 0 0 -1 0 0
> 1 0 0 0 -1 0
> 1 0 0 0 0 -1
>
> Which from my understanding should cover the rest of the contrasts such as
> 2v5 3v6 and etc. Is my understanding of this correct?
>
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>
>
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Re: [Freesurfer] Group effect Contrast for 6 groups

[Greve, Douglas N.,Ph.D.]

Yes, that is correct. It is testing the null hypothesis A=B=C=D=E=F. That 
hypothesis will be rejected if A is different from B-F, which is what you are 
testing. The other contrasts are redundant (and would cause an error if you 
added them to the contrast matrix)z

On 10/16/19 12:03 PM, cody samth wrote:

External Email - Use Caution

Hi,

I'm designing an analysis that will have 6 groups (two factors/three levels). I 
was wondering if I could get some input regarding my contrast for the group 
effect. Based on the group effect contrast under the FSGD examples for 3 groups 
I've written a five line contrast file that compares group 1 against the other 
5 groups.

1-1 0 0 0 0
1 0 -1 0 0 0
1 0 0 -1 0 0
1 0 0 0 -1 0
1 0 0 0 0 -1

Which from my understanding should cover the rest of the contrasts such as 2v5 
3v6 and etc. Is my understanding of this correct?



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[Freesurfer] Group effect Contrast for 6 groups

[cody samth]

External Email - Use Caution

Hi,

I'm designing an analysis that will have 6 groups (two factors/three
levels). I was wondering if I could get some input regarding my contrast
for the group effect. Based on the group effect contrast under the FSGD
examples for 3 groups I've written a five line contrast file that compares
group 1 against the other 5 groups.

1-1 0 0 0 0
1 0 -1 0 0 0
1 0 0 -1 0 0
1 0 0 0 -1 0
1 0 0 0 0 -1

Which from my understanding should cover the rest of the contrasts such as
2v5 3v6 and etc. Is my understanding of this correct?
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