Changes and Enhancements to SAS/STAT Software in V7 and V8

PHREG Procedure

The PHREG procedure includes several MODEL statement options that provide additional control over the optimization process. The ABSCONV= option specifies the absolute function convergence criterion, the FCONV= option specifies the relative function convergence criterion, the GONV= option specifies the relative gradient convergence criterion, and the XCONV= option specifies the relative parameter convergence criterion. The RIDGING= option specifies the technique used to improve the log-likelihood function when its value is less than that of the previous iteration.

PROC PHREG supports the NOTRUNCATE option in the FREQ statement to allow noninteger frequency values to be used in the computations. The default value for the ORDER= option in the OUTPUT statement has been changed from SORTED to DATA.

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