As you write, the code snippet you copied works PER condition, i. e. it orthogonolises the basis functions and all pmods WITHIN one condition - this is not the full design matrix.
Best,
Dom
Last edit: Dominik Bach 2013-03-20
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Hi,
Why the design matrix needs to be orthogonalized? What if it weren't?
Thx,
David
The design matrix is NOT orthogonalised.
Only pmods are orthogonalised with respect to the canonical response.
The reason is that any event elicits a response. A pmod allows you to assess how this general response is modulated by a continuous variable.
Well, in the code, under 'create design matrix', apparently it does:
That's done for all conditions.
Thx
No, the design matrix is not orthogonalised
As you write, the code snippet you copied works PER condition, i. e. it orthogonolises the basis functions and all pmods WITHIN one condition - this is not the full design matrix.
Best,
Dom
Last edit: Dominik Bach 2013-03-20
I see, thx for clarifying this.
So why is orthogonalization within a condition required?
David
Because you want to separate the overall response from the impact of the pmod.