Hello
I have a question about independence between regressors in a modified
FIR model.
The modified FIR model means:
SPM.xBF.length is the same as TR in order to avoid interference
between neighbor scanning.
Two conditions(e.g, A, B) And the order is one. >> Two regressors.
No duration time, so the model is one of event-related designs.
Every image can be classified to condition A or B.
other settings are following:
SPM.xBF.name = 'Finite Impulse Response';
SPM.xBF.length = 14; % length in seconds
SPM.xBF.order = 1; % order of basis set
SPM.xBF.T = 16; % number of time bins per scan
SPM.xBF.T0 = 1; % first time bin (see slice
timing)
SPM.xBF.UNITS = 'scans'; % OPTIONS: 'scans'|'secs' for
onsets
SPM.xBF.Volterra = 1; % OPTIONS: 1|2 = order of
convolution
In such analysis, the independence between the two regressors is
assured? One of my colleagues said No because the sum of those
regressors is almost 1 in every time point.
But, in SPM2, there is no sign to doubt the independence. Even when
SPM.xBF.T (# of time bins pre scan) was set as 1, SPM2 did not show
any warning.
Which is right, SPM2 or my colleague?
I would appreciate your any comment.
Thank you
T.W.
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