Might you have missing data in the dependent variable that causes there to be no valid cases for one of the categories?
System missing values (the periods), by the way, are always excluded, but in a transformation, you can use the sysmis function to handle them. sysmis(x) returns 1 if x is system missing and zero otherwise. And RECODE, for example, has a special keyword, SYSMIS, for referring to system missing.
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of Rayman Mohamed
Sent: Friday, June 17, 2005 7:35 AM
Subject: Re: [SPSSX-L] Unexpected singularities
Hector and Jon,
Thanks for your replies and the heads-up on more efficient
syntax. WRT to Jon's comment, I get the same singularity
message even when I drop all the other predictors, i.e., I
use political affiliations as the only predictors.
I have three related issues that might together help me
clear this up.