Dear Walter,
> How do construct the design matrix in this case
>
> 4 subjects, 3x2 = 6 conditions in 3 runs for every subject
>
> time course for conditions
> session 1: 1 2 1 2 1 2 1 2 1 2 1 2 1
> 2: 3 4 3 4 3 4 3 4 3 4 3 4 3
> 3: 5 6 5 6 5 6 5 6 5 6 5 6 5
> 4: 1 2 1 2 1 2 1 2 1 2 1 2 1
> 5: 3 4 3 4 3 4 3 4 3 4 3 4 3
> 6:
> etc
> 12: 5 6 5 6 5 6 5 6 5 6 5 6 5
>
> Goal: how to specify the to-be-tested contrasts C1>C2, C2>C1, C3>C4,
> C4>C3, C5>C6 and C6>C5 for the group?
> Why should there be 48 elements in the contrast vectors?
> What are the elements?
I would imagine that you have specified 4 subjects (i.e. sessions - S)
with 12 effects per session. These may be the 6 conditions (C) with
two regressors per condition (a and b) (a box car and its
derivative?). If this is the case and the columns correspond to:
S1C1a S1C1b S1C2a S1C2b ... S2C1a S2C1b.....S4C6a S4C6b
Contrast weights testing for the average effect (over these subjects) of
C1 > C2 would look like:
1 0 -1 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0 0 0 0 -1 0 0 0 0 0 0 0 0 0....
With best wishes - Karl
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|