CEA test: Carcinoembryonic antigen test is to detect response to therapy in cancer patients, especially colon cancer, with normal range of less than 2.5 (less than 5 in heavy smokers). Note that a positive test may not always be indicative of cancer.
Os Trigonum Syndrome. An Os Trigonum is a small, extra bone found at the back of the ankle in approximately 5-10% of people. Often it goes completely unnoticed, not causing any problems.
So, for my code I have entered: proc genmod data=want; class period area; model nsum=area period area*period / dist=NB link=log offset=log pop type1; run; I am not really interested in estimates just for area or just for period, rather, I am interested in the difference between the areas over the time period.