For the questions you are trying to answer, you will need several models.
In the above setup, you can remove EV5 and EV6 since they are
redundant; however, I would add EVs for group1 and group 2 as well as
EVs for pre- and post-.
The large model can be used to evaluate the pre-/post-differences
across all subjects, within a single group, or the interaction between
groups (e.g. C4)
Any contrast within a single condition will require a new model.
For C1 - you need a one-sample t-test.
For C2 - you need a one-sample t-test.
For C3 - you need a two-sample t-test.
Best Regards, Donald McLaren
=================
D.G. McLaren, Ph.D.
Research Fellow, Department of Neurology, Massachusetts General Hospital and
Harvard Medical School
Postdoctoral Research Fellow, GRECC, Bedford VA
Website: http://www.martinos.org/~mclaren
Office: (773) 406-2464
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On Thu, Jul 19, 2012 at 7:22 PM, Rongxiang Tang <[log in to unmask]> wrote:
> Dear All,
>
> I'm setting up Glm design and contrasts matrices for my ICA dual regression
> analysis, and would like to confirm couple things.
> I have two groups (exp,contrl, each with a pre and post scan), and I want to
> test if there is a difference in each group before and after the training,
> and if there is a difference between groups, (exp pre vs. contrl pre).
> I run a concat-ica for all of my subjects(pre,post,exp,contrl, each group 22
> subjects, total 88 inputs), and now want to set up the glm for my dual
> regression analysis.
>
> I was wondering how can I combine 1) unpaired t-test(within subjects), and
> 2) paired t-test(between subjects) in the set up...
>
> let's say if I have 2 groups, 2 subjects in each group, pre&post condition:
> Group EV1 EV2 EV3 EV4 EV5
> EV6 EV7 EV8 EV9 EV10
> input1(sub1pre) 1 1 0 0 0
> 1 0 1 0 0 0
> input2(sub2pre) 1 1 0 0 0
> 1 0 0 1 0 0
> input3(sub1post) 1 0 0 1 0
> -1 0 1 0 0 0
> input4(sub2post) 1 0 0 1 0
> -1 0 0 1 0 0
> input5(sub1pre) 2 0 1 0 0
> 0 1 0 0 1 0
> input6(sub2pre) 2 0 1 0 0
> 0 1 0 0 0 1
> input7(sub1post) 2 0 0 0 1
> 0 -1 0 0 1 0
> input8(sub2post) 2 0 0 0 1
> 0 -1 0 0 0 1
>
>
> EV1 EV2
> EV3 EV4 EV5 EV6 EV7 EV8 EV9 EV10
> C1 GROUP1 PRE-MEAN 1 0 0 0
> 0 0 0 ...............................
> C2 GROUP2 POST-MEAN 0 0 0 1
> 0 0 .........................
> C3 GROU1P1PRE>GROUP2PRE 1 -1 0
> .....................................................
> C4 GROUP1PRE>GROUP1POST 0 0...................... 1
> 0...........................................
>
> are the above setup correct?
>
> Thanks,
> Catherine
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