Dear Elif,
if you could send me a copy of your DCM file, then I will have a look
at it. Will take a few days as it's a busy period but I will look into it.
Best wishes,
Klaas
At 15:31 01/07/2005, Elif Ozdemir wrote:
>Hi Klaas,
>
>Thanks for your reply. When I set up the model, I choose one region as a
>driving input (after entering the extrinsic conditions). I tried a model
>that is very similar to the attention model from your group where I entered
>one condition and one region (like photic condition and V1) and then other
>conditions and connections. The model stopped after the first iteration. I
>might be missing something here. So any leads are appreciated!
>
>Thanks
>
>Elif
>
>
>
>On Fri, 1 Jul 2005 09:35:27 +0100, Klaas Enno Stephan
><[log in to unmask]> wrote:
>
> >At 19:54 30/06/2005, Elif Ozdemir wrote:
> >>On Thu, 30 Jun 2005 13:45:14 +0100, Christian Matthiae
> >><[log in to unmask]> wrote:
> >>
> >> >Hi Elif,
> >> >i am not an expert, so i am not completely sure about this.
> >> >But i think there is no problem, as you dont get an error, but only a
> >> >warning. Every DCM matrix contains not specified connections, which can
>not
> >> >be estimated. During estimation these connections get the value Nan,
>which
> >> >is indicated by the displayed warning. So i think your estimation was
> >> >finished correctly. The reason that you get this warning after the first
> >> >step is, that iteration stops, if the changes from one step to the next
>are
> >> >smaller than a threshold (1e-6 i think). This condition is met in your
> >> >analysis after the first step (dp: 1.139079e-21). This is a little
> >> >astonishing for me, but perhaps could be due to a very simple model?
> >> >If i am wrong here one of the spm/dcm should please correct me.
> >> >Hope this helps,
> >> >Christian
> >> >
> >> >
> >> >On Thu, 30 Jun 2005 01:26:49 +0100, Elif Ozdemir <[log in to unmask]
> >> >HARVARD.EDU> wrote:
> >> >
> >> >>Dear all,
> >> >>
> >> >>I am conducting a DCM analysis on a dataset that we acquired from a
> >>subject
> >> >>using a sparse temporal sampling method (TR=15, TA=1.75 sc). I have
> >>defined
> >> >>three VOIs for two (out of four) conditions. When I do the estimation,
>I
> >> >>get the error message below after the first iteration. I have read the
> >> >>previous posts about this error and have the latest DCM updates.
> >> >>
> >> >>After getting the error message, I am still able review the results.
>The
> >> >>histogram is drawn only for B probabilities, not for B modulatory
>effects.
> >> >>In addition, even though the VOIs are circled, there are no numbers.
> >> >>
> >> >>I have replicated the results of the attention data from Dr.Penny's
> >>website
> >> >>without these error messages.
> >> >>
> >> >>Any ideas how to fix this? Any input/help is greatly appreciated!
> >> >>Thanks!
> >> >>
> >> >>Elif
> >> >>
> >> >>"E-Step(-): 1 F: -1.043264e+03 dp: 1.139079e-21
> >> >>Warning: Returning NaN for out of range arguments
> >> >>> In /usr/local/spm2/spm_Ncdf.m at line 76
> >> >> In /usr/local/spm2/spm_dcm_estimate.m at line 72
> >> >> In /usr/local/spm2/spm_dcm_ui.m at line 312"
> >>
> >>Hi Christian,
> >>
> >>Thanks for the message. I have specified several DCMs with conditions
> >>ranging from two to 6, VOIs from 2 to 6 and intrinsic conditions from 2 to
> >>12. None of them worked (at least completely). A and B probabilities are
> >>there. But no numbers on the regions. There are dashed lines instead of
> >>solid ones with red dots around the VOIs.
> >>
> >>In the last DCM model, I had 8 conditions in the design matrix, took two
>of
> >>those conditions to the DCM, had 6 VOIs and 12 intrinsic connections. For
> >>the condition one and two, I had same number of connections (I think 6).
> >>The NaN error message still comes up after the first iteration.
> >>
> >>Any ideas as to how I could make these dashed lines solid and see the
> >>corresponding numbers? Loading DCM.A mat gives me only -1s and 0s.
> >>
> >>Any help is very much appreciated!!!
> >>
> >>Elif
> >
> >
> >
> >Dear Elif,
> >
> >is it possible that you forgot to specify driving inputs for your
> >model? Without such driving inputs, there will be no dynamics
> >whatsoever, and the model will converge at the first iteration.
> >
> >Best wishes
> >Klaas
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