Dear Julie,
there are many different ways to model this: you could use a 2-sample
t-test and include the FA vector as covariate. Alternatively, you could
enter both "years of education" and FA as covariates in a multiple
regression model. To assess correlation with the FA vector, you would
simply weight its column with "1", and the other columns with "0".
Hope this helps,
Volkmar
Am Montag, den 05.01.2009, 12:02 -0500 schrieb Julie E McEntee:
> It's a vector containing the mean FA value for each subject.
>
> Julie E. McEntee, M.A., C.C.R.P.
> Senior Research Program Coordinator
> Department of Psychiatry- Neuroimaging
> Johns Hopkins University School of Medicine
> 600 N. Wolfe St./ Phipps 300
> Baltimore, MD 21287
> Phone: 410-502-0468
> Fax: 410-614-3676
>
> ----- Original Message -----
> From: "MCLAREN, Donald" <[log in to unmask]>
> Date: Monday, January 5, 2009 11:50 am
> Subject: Re: [SPM] fMRI 2nd-level analysis with covariates
> To: Julie E McEntee <[log in to unmask]>
>
>
> > Is the covariate of interest the FA value extracted from a region or
> > the FA
> > value at each voxel?
> >
> > On Mon, Jan 5, 2009 at 10:38 AM, Julie E McEntee <[log in to unmask]>
> > wrote:
> >
> > > Hello SPMers,
> > >
> > > I am using the latest version/update of SPM5 with MatLab 7.0 on
> > Windows XP
> > > Professional 2002, service pack 3.
> > >
> > > I have 1st-level analyses (.con hdr/image files) consisting of the
> > > difference between 2 task conditions for each of 2 groups (patients
> > and
> > > controls).
> > >
> > > There is a statistically significant difference between the 2
> > groups in
> > > years of education. I would like to include this as a "nuisance"
> > variable at
> > > 2nd-level analysis. I would also like to include a "covariate of interest"
> > > (in this case fractional anisotrophy- FA). There is no correlation
> > between
> > > these 2 variables.
> > >
> > > What test should I use at the 2nd-level (and subsequent definition
> > of
> > > contrast weights) to answer the queston:
> > >
> > > Is FA related to the difference in BOLD response between groups?
> > >
> > > Thank-you for your help,
> > >
> > > Julie
> > >
> > > Julie E. McEntee, M.A., C.C.R.P.
> > > Senior Research Program Coordinator
> > > Department of Psychiatry- Neuroimaging
> > > Johns Hopkins University School of Medicine
> > > 600 N. Wolfe St./ Phipps 300
> > > Baltimore, MD 21287
> > > Phone: 410-502-0468
> > > Fax: 410-614-3676
> > >
> >
> >
> >
> > --
> > Best Regards, Donald McLaren
> > =====================
> > D.G. McLaren
> > University of Wisconsin - Madison
> > Neuroscience Training Program
> > Office: (608) 265-9672
> > Lab: (608) 256-1901 ext 12914
> > =====================
> > This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED
> > HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is
> > intended only for the use of the individual or entity named above. If
> > the
> > reader of the e-mail is not the intended recipient or the employee or
> > agent
> > responsible for delivering it to the intended recipient, you are hereby
> > notified that you are in possession of confidential and privileged
> > information. Any unauthorized use, disclosure, copying or the taking
> > of any
> > action in reliance on the contents of this information is strictly
> > prohibited and may be unlawful. If you have received this e-mail
> > unintentionally, please immediately notify the sender via telephone
> > at (608)
> > 265-9672 or email.
>
--
Volkmar Glauche
-
Department of Neurology [log in to unmask]
Universitaetsklinikum Freiburg Phone 49(0)761-270-5331
Breisacher Str. 64 Fax 49(0)761-270-5416
79106 Freiburg http://fbi.uniklinik-freiburg.de/
|