PROC LIFETEST produces two other plots that give useful information about the shape of the hazard function, the log-survival (LS) plot and the log-log survival (LLS) plot. In this section, we’ll see how these plots help determine whether the hazard function can be accurately described by certain parametric models discussed in Chapter 2. We’ll also see how to get smoothed estimates of the hazard function with ungrouped data.

Suppose we specify PLOTS=(S, LS, LLS) in the PROC LIFETEST statement. The S gives us the now-familiar survival curve. LS produces a plot of –log Ŝ(t) versus t. To explain what this plot is good for, we need a little background. From equation (2.6), you can readily see that

Because ...

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