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Hi George,

We generally use option one for most analysis focusing on comparisons of
the groups. But it depends on what the aim of your project is.

Shruti.
On Apr 16, 2015 11:08 AM, "George Chahine" <[log in to unmask]> wrote:

> Dear all,
>
> I have a sort of basic question about group ICA design. I wish to run ICA
> on two groups (control vs patients). We have the following options
> concerning the group analysis:
>
> 1) do the initial ICA definition on all subjects regardless of group, and
> then dual regression on each subject in the analysis.
> 2) do the ICA definition only on the control group, and then dual
> regression on the subjects from both groups. This will decrease false
> negatives.
> 3) do the ICA definition on a large control group (that does not include
> the control subjects in the subsequent analysis) and then dual regression
> on all subjects that will be part of the analysis.
> 4) do ICA on the patients alone and the control group alone, and then do
> dual regression for each group separetely and carry the second level
> analysis on matching networks.
>
> 4 is probably the least preferred option, as it will introduce too much
> bias and false positives. 3 to me seems the best, but I am not sure if it
> is valid to do the initial ICA on subjects outside the main analysis.
>
> I would greatly appreciate your help on this issue.
>
> Best regards,
>
> George
>