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The LIFETEST Procedure |

- 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)
- _STRTUM_, a numeric variable that numbers the strata
- the time variable as given in the TIME statement. In the case of the product-limit estimates, 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 containing the survival function estimates
- SDF_LCL, a variable containing the lower endpoint of the survival confidence interval
- SDF_UCL, a variable containing the upper endpoint of the survival confidence interval

If the estimation uses the product-limit method, then the data set also contains

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

- MIDPOINT, a variable containing the value of the midpoint of the time interval
- PDF, a variable containing the density function estimates
- PDF_LCL, a variable containing the lower endpoint of the PDF confidence interval
- PDF_UCL, a variable containing the upper endpoint of the PDF confidence interval
- HAZARD, a variable containing the hazard estimates
- HAZ_LCL, a variable containing the lower endpoint of the hazard confidence interval
- HAZ_UCL, a variable containing the upper endpoint of the hazard confidence interval

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 method is used or an observation for each time interval if the life table method is used. The product-limit 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.

- any specified BY variables
- _TYPE_, a character variable of length 8 that labels the type of rank test, either "LOG-RANK" or "WILCOXON"
- _NAME_, a character variable of length 8 that labels the rows of the covariance matrix and the test statistics
- the TIME variable, containing the overall test statistic in the observation that has _NAME_ equal to the name of the time variable and the univariate test statistics under their respective covariates.
- all variables listed in the TEST statement

The output is in the form of a symmetric matrix formed by the covariance matrix of the rank statistics bordered by the rank statistics and the overall chi-square statistic. If the value of _NAME_ is the name of a variable in the TEST statement, the observation contains a row of the covariance matrix and the value of the rank statistic in the time variable. If the value of _NAME_ is the name of the TIME variable, the observation contains the values of the rank statistics in the variables from the TEST list and the value of the overall chi-square test statistic in the TIME variable.

Two complete sets of statistics labeled by the _TYPE_ variable are produced, one for the log-rank test and one for the Wilcoxon test.

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