SURVIVAL Statement

The LIFETEST Procedure

SURVIVAL Statement

SURVIVAL options ;

The SURVIVAL statement creates an output SAS data set containing the results of the estimation of the survivor function. Although you can use the OUTSURV= option in the PROC LIFETEST statement to produce the output data set, the SURVIVAL statement enables you to output confidence bands and to specify a transformation of survival time in the computation of the pointwise confidence intervals and the confidence bands. Options in the PROC LIFETEST statements (ALPHA=, INTERVALS=, REDUCEOUT, and TIMELIST=) that applies to the OUTSURV= data can also be specified in the SURVIVAL statements. You can plot these survival estimates using the experimental ODS graphics (see the section "ODS Graphics").

Table 40.2: Summary of SURVIVAL Statement Options

Task	Options	Description
Specify Data Set	OUT=	specifies the output SAS data set
Specify Transformation	CONFTYPE=	specifies the transformation for the computation of pointwise and simultaneous confidence intervals for the survivor function
Specify Confidence Bands	CONFBAND=	specifies the confidence bands to be output
	BANDMAX=	specifies the maximum time for the confidence bands
	BANDMIN=	specifies the minimum time for the confidence bands
Standard Errors	STDERR	outputs the standard errors

BANDMAXTIME=value

BANDMAX=value

specifies the maximum time for the confidence bands. The default is the largest observed event time. If the specified BANDMAX= time exceeds the largest observed event time, it is truncated to the largest observed event time.

BANDMINTIME=value

BANDMIN=value

specifies the minimum time for the confidence bands. The default is the smallest observed event time. For the equal precision band, if the BANDMIN= value is less than the smallest observed event time, it is defaulted to the smallest observed event time.

CONFBAND=keyword

specifies the confidence bands to output. Confidence bands are available only for the product-limit method. You can use the following keywords:

ALL: outputs both the Hall-Wellner and the equal precision confidence bands.
EP: outputs the equal precision confidence band.
HW: outputs the Hall and Wellner confidence band.

CONFTYPE=keyword

specifies the transformation applied to S(t) to obtain the pointwise confidence intervals as well as the confidence bands. The following keywords can be used and the default is CONFTYPE=LOGLOG.

ASINSQRT

the arcsine-square root transformation

$g(x) = \sin^{-1} (\sqrt{x})$

LOGLOG

the log-log transformation

g(x) = log(-log(x))

This is also referred to as the log cumulative hazard transformation since it is applying the logarithmic function log(.) to the cumulative hazard function. Collett (1994) and Lachin (2000) refer it as the complementary log-log transformation.

LINEAR

the identity transformation

g(x) = x

LOG

the logarithmic transformation

g(x) = log(x)

LOGIT

the logit transformation

g(x) = log( [x/(1-x)] )

OUT=SAS-Data-Set

names the SAS data set that contains the survival estimates. If the OUT= option is omitted, PROC LIFETEST creates an output SAS data set with the default name DATAn. If you do not want to create this output SAS data set, set OUT=_NULL_.

STDERR

specifies that the standard error of the survivor function (SDF_STDERR) be output. If the life-table method is used, the standard error of the density function (PDF_STDERR) and the standard error of the hazard function (HAZ_STDERR) are also output.

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