The LIFETEST Procedure

ODS Graphics

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 52.6, along with the required keywords for the PLOTS= option.

Table 52.6: Graphs Produced by PROC LIFETEST

ODS Graph Name

Plot Description

PLOTS=Option

DensityPlot

Estimated density for life-table method

PDF

FailurePlot

Estimated failure function

SURVIVAL(FAILURE)

HazardPlot

Estimated hazard function for life-table method or smoothed hazard for product-limit, Breslow, or Fleming-Harrington method

HAZARD

LogNegLogSurvivalPlot

Log of negative log of the estimated survivor function

LOGLOGS

NegLogSurvivalPlot

Negative log of the estimated survivor function

LOGSURV

SurvivalPlot

Estimated survivor function

SURVIVAL

SurvivalPlot

Estimated survivor function with number of subjects at risk

SURVIVAL(ATRISK=)

SurvivalPlot

Estimated survivor function with pointwise confidence limits

SURVIVAL(CL)

SurvivalPlot

Estimated survivor function with equal-precision band

SURVIVAL(CB=EP)

SurvivalPlot

Estimated survivor function with Hall-Wellner band

SURVIVAL(CB=HW)

SurvivalPlot

Estimated survivor function with homogeneity test p-value

SURVIVAL(TEST)


Additional Dynamic Variables for Survival Plots Using ODS Graphics

PROC LIFETEST passes a number of summary statistics as dynamic variables to the ODS Graphics for survival plots. Table 52.7 and Table 52.8 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 52.7: 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 52.8: 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 The Graph Template Language in Chapter 22: ODS Graphics Template Modification, for the general use of dynamic variables. For the use of the particular dynamic variables shown in this section, see the sections Modifying the Layout and Adding a New Inset Table and Displaying Survival Summary Statistics in Chapter 22: ODS Graphics Template Modification.