Customizing the Kaplan-Meier Survival Plot

Additional Dynamic Variables

PROC LIFETEST passes to the survival plots a number of dynamic variables that contain summary statistics. Some of these dynamic variables are used when you call the %SurvivalSummaryTable macro. Table 1 and Table 2 list these additional dynamic variables for the Kaplan-Meier curves and the life-table curves, respectively. These dynamic variables are not declared in the templates for the survival curves, but you can declare them and use them to enhance the default plots.[23] The names of the dynamic variables depend on the STRATA= suboption of the PLOTS=SURVIVAL option: STRATA=INDIVIDUAL produces a separate plot for each stratum, and STRATA=OVERALL produces one plot that has overlaid curves.

Table 1: Additional Dynamic Variables for Stat.Graphics.ProductLimitSurvival

STRATA= Dynamic Description
OVERLAY StrValj Label for the jth stratum
NObsj Number of observations in the jth stratum
NEventj Number of events in the jth stratum
Medianj Median survival time of the jth stratum
LowerMedianj Lower median survival time of the jth stratum
UpperMedianj Upper median survival time of the jth stratum
PctMedianConfid Confidence of the median intervals, in percentage
INDIVIDUAL NObs Number of observations
NEvent Number of events
Median Median survival time
LowerMedian Lower median survival time
UpperMedian Upper median survival time
PctMedianConfid Confidence of the median intervals, in percentage


Table 2: Additional Dynamic Variables for Stat.Graphics.LifetableSurvival

STRATA= Dynamic Description
OVERLAY StrValj Label for the jth stratum
NObsj Number of observations in the jth stratum
NEventj Number of events in the jth stratum
INDIVIDUAL NObs Number of observations
NEvent Number of events



[23] Because the number of dynamic variables is a function of the number of strata, the template definition cannot automatically contain the correct number of dynamic variables.

Last updated: December 09, 2022