Dear Darren,
thank you for answer.
But I am still puzzled over suitability/applicability of comparing averaged
DCMs (averaging of the same DCMs over subjects = fixed effect analysis, and
then comparing two group DCMs). For example groups 1 and 2 have the same
fully connected regions but group 1 has driving input into region X and
group into region Y. I am interested in conclusion which model (which
location of driving input) is the most suitable for our data.
Michal
> -----Original Message-----
> From: Darren Gitelman [mailto:[log in to unmask]]
> Sent: Tuesday, April 11, 2006 6:41 PM
> To: 'Ing. Michal Mikl'; [log in to unmask]
> Subject: RE: [SPM] DCM comparisons at gorup level
>
>
> Dear Michal:
>
> There are two ways
>
> One is to do DCM model comparison, if for example the groups
> are based on different network models. However, this too
> implements a fixed effects type of analysis. A second was is
> to do a random effects analysis on the relevant DCM
> parameters from the A, B or C matrices. Depending on the
> number of comparisons you may have to correct for multiple
> comparisons.
>
> Darren
>
>
> Darren R. Gitelman, M.D.
> Cognitive Neurology and Alzheimer¹s Disease Center
> Northwestern Univ., 320 E. Superior St., Searle 11-470,
> Chicago, IL 60611
> Voice: (312) 908-9023 Fax: (312) 908-8789
>
>
> | -----Original Message-----
> | From: SPM (Statistical Parametric Mapping)
> | [mailto:[log in to unmask]] On Behalf Of Ing. Michal Mikl
> | Sent: Tuesday, April 11, 2006 2:52 AM
> | To: [log in to unmask]
> | Subject: [SPM] DCM comparisons at gorup level
> |
> | Dear DCM experts,
> |
> | I have question about right algorithm/procedure to compare
> | DCMs at group level. In our study we have 20 subjects.
> | Several DCMs were constructed for each subject. Our goal is
> | to find the most appropriate model for population inferences
> | about effective connectivity.
> |
> | What algorithm/procedure is the best solution to reach our goal?
> |
> | We tried to use averaging of DCMs across individual subjects
> | and subsequently comparing these group-DCMs (various
> | structures of intrinsic connections). But I doubt about this
> | procedure. First, it is only fixed-effect analysis, and
> | second, I don't know if comparing averaged DCMs is appripriate.
> |
> | Thanks for some help
> |
> | Best regards,
> | Michal Mikl
> |
> |
> |
> | ********************************************
> | Ing. Michal Mikl
> | functional Magnetic Resonance Imaging
> | 1st Department of Neurology
> | St. Anne´s University Hospital
> | 656 91, Brno, Czech Republic
> | Phone: +420-543-182-685
> | e-mail: [log in to unmask]
> | ********************************************
> |
>
>
|