Re: [Freesurfer] design matrix problem in qdec

2010-03-01 Thread Douglas N Greve
The last column in the matrix is all 0s. This means that there are no members of that group (PTSDPTSD-diagnostikKG). doug =?iso-8859-1?q?=22br=f...@nmr.mgh.harvard.edu wrote: > Hi to All, > > I have come across a problem using qdec, specified below. What I am trying to > do is to look for an int

[Freesurfer] design matrix problem in qdec

2010-03-01 Thread =?iso-8859-1?Q?=22Br=FChl
Hi to All, I have come across a problem using qdec, specified below. What I am trying to do is to look for an interaction between two discrete variables (diagnostik and PTSD). It is my understanding that this appears to be a common problem. However, is there a way around it, such as conceptuali