1 Jul
2009
1 Jul
'09
12:31 p.m.
Hello, I am trying to run a cortical thickness analysis to look for an interaction between two continuous variables using mri_glmfit. I created an fsgd file including only the two original CVs to investigate main effects and obtained the output. When I added the interaction term (product of the two CVs) as a third continuous variable in my fsgd file and tried to run a dods analysis, I received the message: "ERROR: matrix is ill-conditioned or badly scaled." I don't understand how this could be the case. Is there a simple way to check whether my design matrix is ill-conditioned?
Susie