The script works perfect when I set NCS to a high number (i.e. 10) and have at least 3 alternatives per choice set. However for the current study I want to do a small pilot with just a few choice sets. When I set NCS to 3, or the number of alts per choice set to two, the script does not work. This is the error I am getting:
File ~\mypath\choicedesign\criteria.py:34 in _derr
return dr,vce
UnboundLocalError: cannot access local variable 'vce' where it is not associated with a value.
I have looked around in the code and it seems that the determinant of the fisher information matrix that is returned by getValueAndDerivatives for some reason equals 0 when using few alternatives/choice sets. I have little training in the statistics used here, so it could be that there is a substantial non-code related reason for this. Does any body have any pointers here? As I said, when using a larger number of alternatives/choice sets, the code works fine because the determinant of the initial design information matrix is not 0.
The script works perfect when I set NCS to a high number (i.e. 10) and have at least 3 alternatives per choice set. However for the current study I want to do a small pilot with just a few choice sets. When I set NCS to 3, or the number of alts per choice set to two, the script does not work. This is the error I am getting:
I have looked around in the code and it seems that the determinant of the fisher information matrix that is returned by getValueAndDerivatives for some reason equals 0 when using few alternatives/choice sets. I have little training in the statistics used here, so it could be that there is a substantial non-code related reason for this. Does any body have any pointers here? As I said, when using a larger number of alternatives/choice sets, the code works fine because the determinant of the initial design information matrix is not 0.