The LIFETEST Procedure

OUTSURV= Data Set

You can specify the OUTSURV= option in the PROC LIFETEST statement to create an output data set that contains the following columns:

• any specified BY variables

• any specified STRATA variables, their values coming from either their original values or the midpoints of the stratum intervals if endpoints are used to define strata (semi-infinite intervals are labeled by their finite endpoint)

• STRATUM, a numeric variable that numbers the strata

• the time variable as given in the TIME statement. For METHOD=KM, METHOD=BRESLOW, or METHOD=FH, it contains the observed failure or censored times. For the life-table estimates, it contains the lower endpoints of the time intervals.

• SURVIVAL, a variable that contains the survivor function estimates

• CONFTYPE, a variable that contains the name of the transformation applied to the survival time in the computation of confidence intervals (if the OUT= option is specified in the SURVIVAL statement)

• SDF_LCL, a variable that contains the lower limits of the pointwise confidence intervals for the survivor function

• SDF_UCL, a variable that contains the upper limits of the pointwise confidence intervals for the survivor function

If the estimation uses the product-limit, Breslow, or Fleming-Harrington method, then the data set also contains the following:

• _CENSOR_, an indicator variable that has a value 1 for a censored observation and a value 0 for an event observation

• SDF_STDERR, a variable that contains the standard error of the survivor function estimator (if the STDERR option is specified in the PROC LIFETEST statement)

• HW_LCL, a variable that contains the lower limits of the Hall-Wellner confidence bands (if the CONFBAND=HW option or the CONFBAND=ALL option is specified in the PROC LIFETEST statement)

• HW_UCL, a variable that contains the upper limits of the Hall-Wellner confidence bands (if the CONFBAND=HW option or the CONFBAND=ALL option is specified in the PROC LIFETEST statement)

• EP_LCL, a variable that contains the lower limits of the equal-precision confidence bands (if the CONFBAND=EP option or the CONFBAND=ALL option is specified in the PROC LIFETEST statement)

• EP_UCL, a variable that contains the upper limits of the equal-precision confidence bands (if the CONFBAND=EP option or the CONFBAND=ALL option is specified in the PROC LIFETEST statement)

If the estimation uses the life-table method, then the data set also contains the following:

• MIDPOINT, a variable that contains the value of the midpoint of the time interval

• PDF, a variable that contains the density function estimates

• PDF_LCL, a variable that contains the lower endpoints of the PDF confidence intervals

• PDF_UCL, a variable that contains the upper endpoints of the PDF confidence intervals

• HAZARD, a variable that contains the hazard estimates

• HAZ_LCL, a variable that contains the lower endpoints of the hazard confidence intervals

• HAZ_UCL, a variable that contains the upper endpoints of the hazard confidence intervals

Each survival function contains an initial observation with the value 1 for the SDF and the value 0 for the time. The output data set contains an observation for each distinct failure time if the product-limit, Breslow, or Fleming-Harrington method is used, or it contains an observation for each time interval if the life-table method is used. The product-limit, Breslow, or Fleming-Harrington survival estimates are defined to be right continuous; that is, the estimates at a given time include the factor for the failure events that occur at that time.

Labels are assigned to all the variables in the output data set except the BY variable and the STRATA variable.