Dear Priyantha,
>Dear All,
>
>Would someone please help me with this?
>
>Is it possible to edit the design matrix once it is
>specified and estimated? What I mean is , for example, is it
>possible to add/remove sessions, add/remove covariates, etc
>without really having to redo the whole process? If this is
>possible how does one do it?
>
It is possible, in principle, but I would not recommend it unless you have
a very good idea of what you are doing. The design is specified in the
variables found in the files SPM_fMRIDesMtx.mat and SPMcfg.mat and by
editing these you may, in principle, change certain parts of your design.
> Another question is more general. Is there any particular
>reason as to why it is not possible to go back and make
>corrections at most steps of the spm99b? Some times i
>inadvertantly select the wrong/unintended choice (eg.
>convolving with a gaussian low pass filter rather than the
>hrf..) and then turns out that I do not know how to correct
>this without havingto respesify the whole de-matrix from the
>scratch... Any help in this regard?
>
Generally speaking writing user interfaces is hard and time consuming. As
you go through the specification of your design you will walk down one path
of a large number of possible ones. Every choice you make is equivalent to
choosing one direction at a cross-way. When you, afterwards, realise you
choose the wrong path at one stage you have to trek back to where you went
wrong and choose the new path. This "back-treking" is very tricky to code
considering the huge amount of possible combinations. Now obviously this
"trek-analogy" is more or less valid depending on which choice we are
talking about, and certain things would be relatively straightforward to
change, but a general mechanism would be hard to find as explained above.
>
>Thank you so much.....
>--
Good luck Jesper
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|