Good things to know for the test ... perhaps?

I was talking with Xiaoming after class and he helped me out with a few concepts. These might be useful to know for the test.

1) (Looking at Table 7.2 on pg 235) If you want to compare the RR of CHD for a women with 71-80 mm Hg compared to a man with 101-110 mm Hg, then you divide the two numbers. 10.9 / 2.43 = 4.49 . This method also works when adding interaction terms (Table 7.3). You can not just divide the numbers to get the 95% C.I. for the RR because you have to take into account the covariance. Xiaoming said to use the “lincom” command in STATA to figure this out.

2) (Looking at the STATA output on top of pg 249) If you want to compare the relative risk for CHD of a 75 year old compared to a 45 year old (30 year difference) then you take the coefficient of age (1.04863) and raise it to the 30th power.

Mike