Hi Anderson,

Thank you so much for your reply!

I was thinking of testing with the one-sample ttest whether there is a (within subject) difference between eg the default mode network in two conditions (eg rest and rumination). For this i have made the difference of the dual regression cope outputs for the two conditions. Would a one-sample ttest not make sense in this case? (Or would it just  not make sense to test eg the default mode network in rest per se, which i understand why that would be weird)

Best wishes 

Jacquie 

On Thursday, October 11, 2018, Anderson M. Winkler <[log in to unmask]> wrote:

Hi Jacqueline,

That's right. In general (but not for the dual regression), you could still use the original design as that would accommodate the group differences as nuisance.

For the dual regression, however, it doesn't make much sense to do a 1-sample t-test, because the ICs already have a non-zero average in the locations of the networks they represent. Same applies to strictly positive quantities, such as gray matter volume, fractional anisotropy, or cortical thickness: it doesn't make sense to do a one-sample t-test to check whether the mean is different than zero because it is. That is, there is no negative gray matter volume, so there isn't really anything to be tested.

All the best,

Anderson

On Wed, 19 Sep 2018 at 12:54, Jacqueline Scholl <[log in to unmask]> wrote:

I think i've figured out what the problem was: I tried to do one-sample t-tests from the design matrix above. If now instead I only use the design matrix for doing between-group t-tests and run the one-sample t-tests separately with the -1 option for randomise this work. I was just assuming it would also work in one large contrast design matrix to get randomise to do both (like FLAME does). but happy it's working now :)

On Wed, Sep 19, 2018 at 9:51 AM Jacquelne Scholl <[log in to unmask]> wrote:

ps: I'm calling randomise like this:
randomise_parallel = -i ${newCompFile} -o ${resultsFile} -d ${desListDir}/${ides}.mat -t ${desListDir}/{ides}.con -n 5000 -T -m ${maskFile}

and this is in a loop over the different (25) ICA components and designs (30).

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