On 6/20/17 10:14 AM, marco mcsweeney wrote:
Dear Doug,
thank you so much for getting back to me on this.
I am using Freesurfer version 5.3 with QDEV version 1.4 which gives me
both DODS and DOSS design matrix options. I am a little confused about
DOSS in QDEC as I have read quite a few publications which have used
DOSS in QDEC before. Can you please let me know what the issue with
DOSS in QDEC is?
I don't quite remember what was going wrong. It was only under some
circumstances, but I can't remember what those were. The correct path
forward is to use the mri_glmfit command line program for DOSS.
Also, I have looked at age-cortical thickness interaction using DODS
in Qdec with gender and diagnosis as fixed factors, age as covariate
(demean age as well) and eTIV as nuisance. I did not find any
difference in age-cortical thickness interaction between the 2 groups.
That means you can use DOSS.
Also, I am still a bit unsure about using age as covariate in DOSS
through the command line. Is this appropriate given that DOSS assumes
the same slope in both groups?
There's nothing you have to do other than specify doss after the FSGD
file (and create a new contrast matrix).
Or should age be used as a nuisance factor instead (0 in the design
matrix)?
do you mean contrast matrix? if so, then just specify 0 for the nuisance
colum(s)
Thank you so much again for your help with this.
Best wishes
Marco
On Tue, Jun 20, 2017 at 2:02 PM, Douglas Greve
<gr...@nmr.mgh.harvard.edu <mailto:gr...@nmr.mgh.harvard.edu>> wrote:
DOSS should not be used with QDEC as it may or may not do the
right thing. Is it not disabled? What version are you using?
To answer your question, if you want to use DOSS and you're
interested in the diff bet groups, then first test for an
interaction between group and covariate. If that is not
significant, then use DOSS
On 6/20/17 5:05 AM, marco mcsweeney wrote:
Dear Freesurfer experts,
I have a quick question regarding the appropriate design (DOSS or
DODS) to be used with QDEC when comparing 2 groups for cortical
thickness and LGI values.
So far I have used DODS first to look for an age-cortical
thickness interaction in both groups. I used the real ages and
also demeaned the age variable in my analysis. I entered age as a
covariate and as a nuisance factor also. I have gender and
diagnosis as discrete and eTIV as nuisance in both analysis.
Neither was significant.
After this I used DOSS in QDEC to compare groups groups for both
cortical thickness and LGI.
My questions relates to the use of age as a covariate in DOSS. Is
it appropriate to enter age as covariate in DOSS given that DOSS
assumes that both groups have the same slope? I have looked
through the archives and online for an answer to this but I am
still a bit confused.
Any help or advice on this would be greatly appreciated.
Thank you so much in advance.
Best wishes
Marco
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
<mailto:Freesurfer@nmr.mgh.harvard.edu>
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
<https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer>
_______________________________________________ Freesurfer mailing
list Freesurfer@nmr.mgh.harvard.edu
<mailto:Freesurfer@nmr.mgh.harvard.edu>
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
<https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer> The
information in this e-mail is intended only for the person to whom
it is addressed. If you believe this e-mail was sent to you in
error and the e-mail contains patient information, please contact
the Partners Compliance HelpLine at
http://www.partners.org/complianceline
<http://www.partners.org/complianceline> . If the e-mail was sent
to you in error but does not contain patient information, please
contact the sender and properly dispose of the e-mail.
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
_______________________________________________
Freesurfer mailing list
Freesurfer@nmr.mgh.harvard.edu
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
The information in this e-mail is intended only for the person to whom it is
addressed. If you believe this e-mail was sent to you in error and the e-mail
contains patient information, please contact the Partners Compliance HelpLine at
http://www.partners.org/complianceline . If the e-mail was sent to you in error
but does not contain patient information, please contact the sender and properly
dispose of the e-mail.
