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Dear Frederik,

These two ways are equivalent, just you don't need the first row in the first way as your first condition will be your baseline and the differences will be defined relative to it. So:

0 1 0 0
 0 0 1 0
 0 0 0 1

Whether to prefer the first or the second way, depends on how you want to interpret the results. For instance, if you thing that the two main effects should affect different connections then it would make sense to use the second way.

Best,

Vladimir


On Mon, Dec 14, 2015 at 1:01 PM, Frederik Van de Steen <[log in to unmask]> wrote:
Dear DCM experts,

I have two questions regarding the design for ERP's when using DCM. If i have a factorial design (2 x 2) what is the best way to set up the design?
e.g. include 4 effects:
1 0 0 0
0 1 0 0
 0 0 1 0
 0 0 0 1

or 3 and than something like

-1 1 0 0
-1 0 1 0
-1 0 0 1

cheers

Frederik