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help > RE: ConcatR=1 and PPI regressors with no variance
May 27, 2016 03:05 PM | Donald McLaren
RE: ConcatR=1 and PPI regressors with no variance
You only selected a subset of tasks for the initial PPI model. The
concatR=1 option uses all the tasks in the SPM model for the
concatenated PPI model. However, the concatenation feature pulls
from the initial PPI model.
The way the code is written is that it builds a PPI column for each task based on the task list from the task analysis SPM model, then it goes to find the PPI term for that task in the initial PPI model. As it can't find that PPI term as its not in the initial model, the column is set to all 0s.
In some future version of the code, there will be a change that will stop this from happening. However, its not high on the priority list as it has minimal effects.
Two solutions:
(1) ignore this issue as it won't impact the results using standard analytical methods; or
(2) specify all conditions in the P.Tasks parameter setting.
My personal opinion is to specify all conditions in the P.Tasks parameter setting.
The way the code is written is that it builds a PPI column for each task based on the task list from the task analysis SPM model, then it goes to find the PPI term for that task in the initial PPI model. As it can't find that PPI term as its not in the initial model, the column is set to all 0s.
In some future version of the code, there will be a change that will stop this from happening. However, its not high on the priority list as it has minimal effects.
Two solutions:
(1) ignore this issue as it won't impact the results using standard analytical methods; or
(2) specify all conditions in the P.Tasks parameter setting.
My personal opinion is to specify all conditions in the P.Tasks parameter setting.
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Title | Author | Date |
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Gina Joue | May 27, 2016 | |
Donald McLaren | May 27, 2016 | |