Dear all,
I have a question regarding the output from selxavg3-sess. I noticed that within an analysis there is a X.mat that looks like a design matrix -- however is this used at any stage of the analysis? The help message in selxavg3-sess reads:
"This program will construct the design matrix for each run, fit the GLM, save regression coefficients, compute contrasts and significances of contrasts. The runs are combined together so the output is the average across runs (some would call this a "second-level" analysis)."
so this looks like that x.mat is constructed and used for each run (and not saved by default). This then looks like X.mat is not used in the analysis -- it is just there for illustrative purposes? or have I misinterpreted the help message.
If this is correct (i.e. X.mat in the output is not used) when making contrasts using mkcontrast-sess, is there a way to parametrically modulate each run? e.g. to model behavioural changes per run etc.
Cheers,
Dr Kevin AquinoResearch fellow,
Sir Peter Mansfield Magnetic Resonance Center, The University of Nottingham.
Honorary Research Fellow
School of Physics, Faculty of Science, University of Sydney
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