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Problem Note 49838: TWOSAMPLESURVIVAL statement options EVENTSPERGROUP=, GROUPEVENTS=, and EVENTSTOTAL= produce incorrect results

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In SAS 9.3 TS1M0 and SAS 9.3 TS1M1, the EVENTSPERGROUP= and GROUPEVENTS= options in the TWOSAMPLESURVIVAL statement in PROC POWER produce incorrect results. In addition, the power computed from the EVENTSTOTAL= option is incorrect. This surfaces both when solving for POWER (computed Power is wrong) and when solving for EVENTSTOTAL (the computed Event Total values are correct, but the computed Actual Power value is incorrect).

As a workaround, do not specify the EVENTSPERGROUP=, GROUPEVENTS= or EVENTSTOTAL= options. You should instead use another sample size specification and allocation method available in the TWOSAMPLESURVIVAL statement. Note that in SAS 9.3 TS1M2 (SAS/STAT 12.1), the EVENTSPERGROUP= and GROUPEVENTS= options have been removed from the procedure. Also, the computations for Power and Acual Power in the EVENTSTOTAL= option have been corrected.



Operating System and Release Information

Product FamilyProductSystemProduct ReleaseSAS Release
ReportedFixed*ReportedFixed*
SAS SystemSAS/STATz/OS9.312.19.3 TS1M19.3 TS1M2
Microsoft® Windows® for x649.312.19.3 TS1M19.3 TS1M2
Microsoft Windows Server 2003 Datacenter Edition9.312.19.3 TS1M19.3 TS1M2
Microsoft Windows Server 2003 Enterprise Edition9.312.19.3 TS1M19.3 TS1M2
Microsoft Windows Server 2003 Standard Edition9.312.19.3 TS1M19.3 TS1M2
Microsoft Windows Server 2003 for x649.312.19.3 TS1M19.3 TS1M2
Microsoft Windows Server 20089.312.19.3 TS1M19.3 TS1M2
Microsoft Windows Server 2008 for x649.312.19.3 TS1M19.3 TS1M2
Microsoft Windows XP Professional9.312.19.3 TS1M19.3 TS1M2
Windows 7 Enterprise 32 bit9.312.19.3 TS1M19.3 TS1M2
Windows 7 Enterprise x649.312.19.3 TS1M19.3 TS1M2
Windows 7 Home Premium 32 bit9.312.19.3 TS1M19.3 TS1M2
Windows 7 Home Premium x649.312.19.3 TS1M19.3 TS1M2
Windows 7 Professional 32 bit9.312.19.3 TS1M19.3 TS1M2
Windows 7 Professional x649.312.19.3 TS1M19.3 TS1M2
Windows 7 Ultimate 32 bit9.312.19.3 TS1M19.3 TS1M2
Windows 7 Ultimate x649.312.19.3 TS1M19.3 TS1M2
Windows Vista9.312.19.3 TS1M19.3 TS1M2
Windows Vista for x649.312.19.3 TS1M19.3 TS1M2
64-bit Enabled AIX9.312.19.3 TS1M19.3 TS1M2
64-bit Enabled HP-UX9.312.19.3 TS1M19.3 TS1M2
64-bit Enabled Solaris9.312.19.3 TS1M19.3 TS1M2
HP-UX IPF9.312.19.3 TS1M19.3 TS1M2
Linux9.312.19.3 TS1M19.3 TS1M2
Linux for x649.312.19.3 TS1M19.3 TS1M2
Solaris for x649.312.19.3 TS1M19.3 TS1M2
* 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.