If the categorical variable is ordered, you can treat it as continuous. Otherwise, you need to create 11 dummy variables to represent the 12 categories. You would use these dummy variables as covariates. You can create them using the DEFINE command.
June Zhou posted on Friday, February 10, 2012 - 10:20 am
Thank you very much for your prompt reply, Dr. Muthen!
The categorical variable is not ordered.
My understanding is that if I coded a level by 1 and others 0, and make it 11 dummy variables, what I am doing is to compare this level with the 12th level (reference group). Is coding method the same if I'd like to compare each level with all other levels?