Dear Freesurfer experts,
A while ago I sent the question below to the FS mailinglist, but it was never answered... Would anyone be able to help me with this issue?
Thank you very much in advance!
Best wishes, Lizanne
Dear Freesurfer experts,
I am modelling multiple covariates (age, SES, nr of symptoms and nr of symptoms2) in one subject group. For the quadratic term I added a column in the fsgd-file. I want to visualize the effect of nr of symptoms, either their linear or their quadratic effects. I therefore made two contrasts:
The effect of symptoms:
0 0 1 0
And the effect of symptoms2:
0 0 0 1
I would like to model these two effects together in one contrast, to visualize the total effect of symptoms. I tried the following contrast:
0 0 1 0
0 0 0 1
But the result is very different from the two individual contrasts. I get large (non-overlapping) clusters of significant effect in the two separate contrasts, but with the combined contrasts I get none. What would be the appropriate contrast if I want to visualize all regions with the effects of symptoms, including both linear AND quadratic effects?
Thank you very much for your help
Best wishes, Lizanne
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That is an F-test that should more-or-less be an OR between your two t-tests. I don't know why you are seeing nothing, but the F-test can be non-intuitive. If you want to test an AND, then you will need to perform a conjunction (use mri_concat sig1.mgh sig2.mgh --conjunct --o conjunction.mgh
doug
On 10/02/2014 09:34 AM, Schweren, LJS (med) wrote:
Dear Freesurfer experts,
A while ago I sent the question below to the FS mailinglist, but it was never answered… Would anyone be able to help me with this issue?
Thank you very much in advance!
Best wishes,
Lizanne
Dear Freesurfer experts,
I am modelling multiple covariates (age, SES, nr of symptoms and nr of
symptoms2) in one subject group. For the quadratic term I added a column in
the fsgd-file. I want to visualize the effect of nr of symptoms, either
their linear or their quadratic effects. I therefore made two contrasts:
The effect of symptoms:
0 0 1 0
And the effect of symptoms2:
0 0 0 1
I would like to model these two effects together in one contrast, to visualize the total effect of symptoms. I tried the following contrast:
0 0 1 0
0 0 0 1
But the result is very different from the two individual contrasts. I get
large (non-overlapping) clusters of significant effect in the two separate
contrasts, but with the combined contrasts I get none.
What would be the appropriate contrast if I want
to visualize all regions with the effects of symptoms, including both linear AND quadratic effects?
Thank you very much for your help
Best wishes, Lizanne
De inhoud van dit bericht is vertrouwelijk en alleen bestemd voor de geadresseerde(n). Anderen dan de geadresseerde(n) mogen geen gebruik maken van dit bericht, het niet openbaar maken of op enige wijze verspreiden of vermenigvuldigen. Het UMCG kan niet aansprakelijk gesteld worden voor een incomplete aankomst of vertraging van dit verzonden bericht.
The contents of this message are confidential and only intended for the eyes of the addressee(s). Others than the addressee(s) are not allowed to use this message, to make it public or to distribute or multiply this message in any way. The UMCG cannot be held responsible for incomplete reception or delay of this transferred message.
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-
Douglas N Greve -
Schweren, LJS (med)