02-08-2012 01:51 PM
I have a question regarding PROC MIXED.
I am setting up a linear mixed model as follow:
PROC MIXED data=work.sample covtest;
class v1 v2;
model dv = / solution;
random intercept / subject=v1 solution v vcorr;
random intercept / subject=v2 solution v vcorr;
v1 and v2 are categorical variables, each having more than 100 categories.
I assume that I have set v1 and v2 to be uncorrelated. Am I right?
The analysis takes me a day to complete. Is there anyway to make the syntax more efficient so that it will run faster?
How can I obtain the correlation between v1 and v2? Which covariance structure should I choose? (I am only interested in (1) whether v1 and v2 are correlated, and (2) the magnitude of correlation between v1 and v2.
Thank you very much for your help!