Hi all,

I am trying to specify a DCM model derived based on a 2 x 2 factorial design.

First, I recombined the onsets of my 4 cells (A1 + A2; B1 + B2; A1 + B1; A2 + B2) to get the 4 conditions representing all 2 main effects.

When specifying the spm model, I get the message under my design matrix: gray -à  ß not uniquely defined…

Indeed there are some overlap of onsets as these are the combinations, but this is the same as in the example data from the SPM homepage.

Additionally it is also not possible to specify the DCM model…

Any help? Many thanks

boris