Hi Laura,
The "-volreg_warp_dxyz 2.5" option is both to force
the output to be 2.5 mm^3 and to make it clear what
it will be. If your data generates a default of 2,
sure, either remove the option or change it to 2.
Many people like to have the final dimension stated
explicitly.
The MIN_OUTLIER and NL_warp options are not required,
but are recommended. It is up to you.
Look up the regress_make_corr_vols option, and see
how it is applied in your script. By "just for
entertainment", I mean the option could be removed
without affecting the analysis. It is just to
compute maps of correlation against average WMe and
subject ventricles.
The cluster simulation is mostly a demonstration of
it could be done at the group level.
- rick