It will not
On 10/13/16 10:34 AM, Eelco van Duinkerken wrote:
Ah sorry for the low level of info. I am aiming to do a simple group
comparison, where I'm comparing thickness between controls and obese
or T2DM patients, regressing out the effect of age, sex and,
hypertension. So I created one thickness file with fwhm 10 containing
all participants of the 3 groups.
The contrast file looks like this:
1 0 -1 0 0 0 for controls vs T2DM
1 -1 0 0 0 0 for controls vs obese
0 1 -1 0 0 0 for obese vs T2DM, although there I do not expect
something to happen
And the GLM works fine (differences in the first and second contrast),
but I was wondering whether the fact that the groups are unbalanced
might influence the results in some way.
Thanks,
Eelco
2016-10-13 11:17 GMT-03:00 Bruce Fischl <fis...@nmr.mgh.harvard.edu
<mailto:fis...@nmr.mgh.harvard.edu>>:
Hi Eelco
it depends on how you setup your GLM. Are you trying to regress
out the effects of obesity in some way? If you give us more
details I expect someone else can answer your question (Doug!)
cheers
Bruce
On Thu, 13 Oct 2016, Eelco van Duinkerken wrote:
Thanks for the quick reply!
So if I understand correctly, the power of say the controls
vs. diabetes
(indeed it is type 2 diabetes) comparison is constrained by
the sample size
of the obese group?
2016-10-13 11:02 GMT-03:00 Bruce Fischl
<fis...@nmr.mgh.harvard.edu <mailto:fis...@nmr.mgh.harvard.edu>>:
Hi Eelco
it isn't really a question of whether our implementation is
senstitive to
this. It's that in general your power will be
constrained by the
size of
the smaller group (I assume this is Type 2 diabetes by
the way).
cheers
Bruce
On Thu, 13 Oct 2016, Eelco van Duinkerken wrote:
> Hi all,
> I am using FS with data from 2 different studies that were
acquired on the
> same MRI-machine with the same T1 and FLAIR sequences.
Unfortunately, the
> group sizes are not very balanced, with 31 controls,
16 obese
and 32
> diabetes patients.
>
> Is the GLM for thickness used in FS very sensitive to this
unequal group
> size?
>
>
> Thanks for the help,
>
> Eelco
>
>
_______________________________________________
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.
--
Eelco van Duinkerken, PhD
Pontifícia Universidade Católica | Department of Psychology |
R. Marquês de São Vicente 225 | Gávea, Rio de Janeiro - RJ |
CEP 22451-900 |
Brasil |
E-mail: e.vanduinker...@vumc.nl
<mailto:e.vanduinker...@vumc.nl> | Phone: +55-21-35271855
<tel:%2B55-21-35271855> |
http://lattes.cnpq.br/7180895567820901
<http://lattes.cnpq.br/7180895567820901>
&
VU University Medical Center | Department of Medical Psychology |
De Boelelaan 1117 | 1081 HV | Amsterdam | The Netherlands
_______________________________________________
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.
--
Eelco van Duinkerken, PhD
Pontifícia Universidade Católica | Department of Psychology |
R. Marquês de São Vicente 225 | Gávea, Rio de Janeiro - RJ | CEP
22451-900 | Brasil |
E-mail: e.vanduinker...@vumc.nl <mailto:e.vanduinker...@vumc.nl> |
Phone: +55-21-35271855 | http://lattes.cnpq.br/7180895567820901
&
VU University Medical Center | Department of Medical Psychology |
De Boelelaan 1117 | 1081 HV | Amsterdam | The Netherlands
_______________________________________________
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.
