Differences in standard error estimates between the two procedures are due to differences in the algorithms they use for covariance matrix estimation. Specifically, when inverting the Hessian matrix PROC QLIM uses a G4 inverse which satisfies all four Moore-Penrose conditions while PROC LIFEREG uses a G2 inverse which satisfies only two Moore-Penrose conditions.

Operating System and Release Information

Product Family	Product	System	SAS Release
			Reported	Fixed*
SAS System	SAS/ETS	IRIX
		HP-UX IPF
		AIX
		HP-UX
		ABI+ for Intel Architecture
		64-bit Enabled Solaris
		64-bit Enabled HP-UX
		64-bit Enabled AIX
		Windows Vista
		Windows Millennium Edition (Me)
		WINDOWS/NTSV
		Microsoft Windows XP Professional
		Microsoft Windows Server 2003 Standard Edition
		Microsoft Windows Server 2003 Enterprise Edition
		Microsoft Windows Server 2003 Datacenter Edition
		Microsoft Windows NT Workstation
		Microsoft Windows 2000 Professional
		Microsoft Windows 2000 Server
		Microsoft Windows 2000 Datacenter Server
		Microsoft Windows 2000 Advanced Server
		Microsoft Windows 95/98
		Windows
		OS/2
		Microsoft® Windows® for x64
		Microsoft Windows XP 64-bit Edition
		Microsoft Windows Server 2003 Enterprise 64-bit Edition
		Microsoft Windows Server 2003 Datacenter 64-bit Edition
		Microsoft® Windows® for 64-Bit Itanium-based Systems
		OpenVMS VAX
		z/OS
		Linux
		Linux on Itanium
		OpenVMS Alpha
		Solaris
		Solaris for x64
		Tru64 UNIX

* For software releases that are not yet generally available, the Fixed Release is the software release in which the problem is planned to be fixed.

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Type:	Usage Note
Priority:
Topic:	Analytics ==> Regression SAS Reference ==> Procedures ==> LIFEREG SAS Reference ==> Procedures ==> QLIM

Date Modified:	2008-01-10 17:28:45
Date Created:	2007-12-18 15:02:07