> I am trying to run a one-sample ttest with 3dttest. I would like to
> ask you what is the criterion to choose the constant value (i.e., bval
> for -base1 option). Is a value of "0" correct?
0 is most likely the value most people set for -base1, but it doesn't have to. The criterion is totally in your hands because you are supposed to know what you want to test against.
Gang