The LIFETEST Procedure
Statistical procedures use ODS Graphics to create graphs as part of their output. ODS Graphics is described in detail in Chapter 21: Statistical Graphics Using ODS.
Before you create graphs, ODS Graphics must be enabled (for example, by specifying the ODS GRAPHICS ON statement). For more information about enabling and disabling ODS Graphics, see the section Enabling and Disabling ODS Graphics in Chapter 21: Statistical Graphics Using ODS.
The overall appearance of graphs is controlled by ODS styles. Styles and other aspects of using ODS Graphics are discussed in the section A Primer on ODS Statistical Graphics in Chapter 21: Statistical Graphics Using ODS.
The survival plot is produced by default; other graphs are produced by using the PLOTS= option in the PROC LIFETEST statement. You can reference every graph produced through ODS Graphics with a name. The names of the graphs that PROC LIFETEST generates are listed in Table 56.7, along with the required keywords for the PLOTS= option.
Table 56.7: Graphs Produced by PROC LIFETEST
|
ODS Graph Name |
Plot Description |
PLOTS=Option |
|---|---|---|
|
DensityPlot |
Estimated density for life-table method |
|
|
FailurePlot |
Estimated failure function |
|
|
HazardPlot |
Estimated hazard function for life-table method or smoothed hazard for product-limit, Breslow, or Fleming-Harrington method |
|
|
LogNegLogSurvivalPlot |
Log of negative log of the estimated survivor function |
|
|
NegLogSurvivalPlot |
Negative log of the estimated survivor function |
|
|
SurvivalPlot |
Estimated survivor function |
|
|
SurvivalPlot |
Estimated survivor function with number of subjects at risk |
|
|
SurvivalPlot |
Estimated survivor function with pointwise confidence limits |
|
|
SurvivalPlot |
Estimated survivor function with equal-precision band |
|
|
SurvivalPlot |
Estimated survivor function with Hall-Wellner band |
|
|
SurvivalPlot |
Estimated survivor function with homogeneity test p-value |
PROC LIFETEST passes a number of summary statistics as dynamic variables to the ODS Graphics for survival plots. Table 56.8 and Table 56.9 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. 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 with overlaid curves.
Table 56.8: 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 percent |
|
|
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 interval in percent |
Table 56.9: 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 |
See the section Dynamic Variables in Chapter 23: Customizing the Kaplan-Meier Survival Plot, for information about all of the dynamic variables that are available for use in the ODS Graphics survival plot. For the use of the particular dynamic variables shown in this section, see the sections Adding a Small Inset Table with Event Information and Adding an External Table with Event Information in Chapter 23: Customizing the Kaplan-Meier Survival Plot.