Hi Jim,

1.Is it appropriate or valid to do group statistical tests on these synthesized HRFs?

I am not so sure what you exactly meant by doing ¡° group statistical tests on these
synthesized HRFs ¡°. If you want to do statistical analysis for each subject in
3dDeconvolve with option -fout or -tout, then it is perfectly OK with percentage scores
since those F and/or T statistic quantities are supposed to be dimensionless, and the
percentage conversion would not change their values.

2.Is there any rule of thumb about choosing the delta-t (-dt) interval in order to maintain
validity of the synthetic time courses?

If you are talking about the -dt option in 3dcalc, you'd better keep it as your TR consistently. Any finer dt would not help you gain any statistical power or visual effect
since it is just interpolation.

Gang Chen