[Mne_analysis] Do I need to setup mri and do watershed etc procedure every time I re-analyze the data

[Eric Larson]

>> When I checked the log file of the outputs of the mne_do_forward_solution
>> and mne_do_inverse_operator from the two times of analysis, it seems there
>> are no difference except for the part of SSP and the SVD result due to that.
>> All the correct files are used when I redo the analysis.
>
> SSP is independent of the source space and the forward operator.
> So it is a bit weird.

As Alex said, SSP is independent from the source/forward calculations,
so SSP should not affect that. However, it sounds like you might also
be doing the inverse calculation (mne_do_inverse_operator). This step
will depend on the SSP because the inverse operator requires the noise
covariance matrix (which should have SSP applied to it).

Eric