> if I want to obtain the correlation coefficient for my seed time course regressor.
> I need to take the square root of the R^2.

In addition to the square root part, you also need to assign the proper sign, which can be obtained from the corresponding beta or t-value for the seed time series. For example:

3dcalc -a subj01+tlrc'[SubbrickForR2]' -b subj01+tlrc'[SubbrickForBeta]' -expr 'ispositive(b)*sqrt(a)-isnegative(b)*sqrt(a)' -prefix ...

> since I have the additional motion parameters. Is it correct to do? I'm getting the same
> R^2 value for the partial R^2 of the seed time course regressor as the full R^2. Is this
> correct? Is this a result of having placed the motion parameters as part of the base
> model (using -stim_base).

Well, the fact that the partial R^2 of the seed time course regressor is the same as the full R^2 in this case simply because you have only one regressor (seed time series) in addition to those regressors in the base model. If you treat the motion parameters as normal regressors (*not* part of the base model), then the partial R^2 of the seed time course regressor would be different from (and smaller than) the full R^2 (which would be the total amount of accountability of the six motion parameters plus the seed time series).

Gang



Edited 1 time(s). Last edit at 06/13/2013 06:39PM by Gang.