ZhiLiangLong wrote:
Hi doug
Thanks for your suggestions. I have another two questions:
1: I can't clearly understand that why i should firstly run DODS to
find interaction between my group variables and age,then run DOSS to
obtain difference between groups specified in my contrast files if
there are no interactions as you suggested.If the interactions
exist,does it mean that DOSS is not suitable for this situation and
only DODS can be used ?
If there is an interaction, then DOSS is not suitable because there is
no simple difference between the groups.
2: If i want to obtain the main effect of factor(difference between
the three groups),how can i setup my contrast file?
Do a search on our Wiki for FSGD. There's a page of examples there,
including an example of your current design.
doug
Hope you can give me some suggestions
At 2011-10-12 00:21:34,"Douglas N Greve" <gr...@nmr.mgh.harvard.edu> wrote:
>Yes, that looks correct. Since you have a covariate as a nuisance
>variable, you should first run your analysis with a DODS model
>(different-offset, different-slope) and look for an interaction between
>your group variables and age (the contrasts are similar, swap the first
>6 numbers with the last 6 zeros). If you do not find an interaction,
>then re-run the analysis with DOSS and use a contrast that has 7
>numbers: the first 6 as you have given, the last number = 0.
>
>doug
>
>ZhiLiangLong wrote:
>> Hi all :
>> I'm performing general linear model (GLM) analysis in the surface,the
>> attachments above are FSGD file and contrast files(the last three
>> attachments).i wonder if my contrast files are correct.
>> the attachment named diff-C-H-thickness.txt is about difference
>> between C and H and the last two are about difference between C and p
>> and difference between P and H,Here,C H and P represent three groups
>> Any suggestions appreciated
>>
>>
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>>
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>--
>Douglas N. Greve, Ph.D.
>MGH-NMR Center
>gr...@nmr.mgh.harvard.edu
>Phone Number: 617-724-2358
>Fax: 617-726-7422
>
>Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting
>FileDrop: www.nmr.mgh.harvard.edu/facility/filedrop/index.html
>
--
Douglas N. Greve, Ph.D.
MGH-NMR Center
gr...@nmr.mgh.harvard.edu
Phone Number: 617-724-2358
Fax: 617-726-7422
Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting
FileDrop: www.nmr.mgh.harvard.edu/facility/filedrop/index.html
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