In PROC PHREG, how do you set a continuous variable at a certain value as the reference level? For example, suppose x = 3.5, 3.6, 4.3, 5.4 and we want x = 6 to be the reference level. How would you do this in SAS?
Would this be correct:
data new; set old; x1 = (x=3.5); x2 = (x= 3.6); x3 = (x = 4.3); x4 = (x= 5.4); proc phreg data = new; class x ( ref = '6'); model time*censor(0) = x1 x2 x3 x4 /r1; run;
Edit. Actually, could one just use the point estimate of the coefficient of $x$? In other words suppose the estimated coefficient for $x$ is $0.512$. Then the hazard ratio between $x = 3.5$ and $x = 6$ would be $\exp(0.512(3.5-6))$, the hazards ratio between $x = 3.6$ and $x = 6$ would be $\exp(0.512(3.6-6))$ etc...?
So there is no need to even form these groups? Just do the following:
proc phreg data = new; model time*censor(0) = x /r1; run;