Ｈｉ，
Ｉ have the same problem. I ran a temporal concatenation over 11 subjects. Each subject has 3 sessions, and I first concatenate the sessions for each subject first (since not all sessions have the same number of time points). After this, each subject has a data set of 609 scans. melodic gave me a total of 236 IC components.From component 172, it give a negative variance count.
I will follow up on this thread.
Thanks,
Lingling
----- Original Message ----
From: Christian F. Beckmann <[log in to unmask]>
To: [log in to unmask]
Sent: Tuesday, February 26, 2008 6:02:57 AM
Subject: Re: [FSL] group ica
Hi,
this should not happen, it might be an overflow somewhere due to
really huge data, can you tar up a report foleder and upload it to
http://www.fmrib.ox.ac.uk/cgi-bin/upload.cgi
and send me the upload ID, please.
Thanks
Christian
> Hi Christian,
>
> Sorry, I still have questions to need your kind helps.
>
> From the group ICA output results, sometimes I can see the last
> component has negative variance proportion value, like -1.06% of
> explained variance; -0.61% total variance. I am confused with it.
> Would
> you please explain it for me?
> In addition, group ICA also has a simple plot and a boxplot that show
> the relative effect size across the different sessions/subjects, which
> come from the values in the first column of matrix s..txt I guess. My
> questions are what the physics meanings of these values is? How to
> compute the values and they have units? What does negative value mean?
> Sorry to bother you so much.
>
> Any help would be great appreciated!
>
> With best regards,
> Weiming
>
>
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