Hi Gang,
> The problem for your numbers is this. 2500 for run 3 is
> troublesome becuase the signal value of 2450 for Task A is
> below the baseline value of 2500: Do you have a real
> deactivation? Of course that would give you "negative" percent
> signal change.
I suppose I have a "deactivation" to Task A when compared to Task B (which it is alternating with in run 3), but the same signal value of 2450 would be an "activation" when Task A is compared to fixation (which it is alternating with in run 1).
That's why I wasn't sure if it was a good idea to concatenate the runs and analyze them together.
I know these numbers are just for example, but it is possible to have a situation like this - where the same value falls above baseline in one run and below baseline in another depending on how the baseline is calculated.
Kara