I have data from a longitudinal parallel groups study where there are 46 subjects randomized to 1 of 5 treatment groups, each subject with roughly 13 observations over time on a given outcome measure. The data trends in a U-shape over time, thus the quadratic term in the model. 4 active treatments are tested against placebo.

I am trying to decide whether it's more appropriate to use a repeated statement

repeated/ subject=subjid;

or a random statement

random int time /subject = subjid ;

Can you help me understand the differences in the model implications based on whether the repeated or random statement is used in SAS?


Check out this link, it demonstrates why and when to use random vs repeated or both! http://www.theanalysisfactor.com/repeated-and-random-2/


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.