Problem Note 42698: Incorrect p-values may be reported for a one-sided or equivalence test
For a one-sided (SIDES=L or SIDES=U) or equivalence (TOST) test based on the normal ratio (TEST=RATIO DIST=NORMAL) with a paired design, two-sample design, or a crossover design with the IGNOREPERIOD option, if the "group 2" sample mean is negative, then the p-values reported are incorrect. The p-values are actually equal to one minus the displayed p-values. For the equivalence test, the Upper and Lower p-values should be adjusted in this manner first, then the Overall p-value is computed as the larger of these two adjusted values. "Group 2" here is the second member of a pair for paired designs, the second group for two-sample designs, and the second treatment for crossover designs with the IGNOREPERIOD option.
If all of the above criteria are met, you can work around this issue by negating the group 2 variable in data step code and rerunning the analysis.
Operating System and Release Information
SAS System | SAS/STAT | z/OS | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft® Windows® for 64-Bit Itanium-based Systems | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft Windows Server 2003 Datacenter 64-bit Edition | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft Windows Server 2003 Enterprise 64-bit Edition | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft Windows XP 64-bit Edition | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft® Windows® for x64 | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft Windows Server 2003 Datacenter Edition | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft Windows Server 2003 Enterprise Edition | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft Windows Server 2003 Standard Edition | 9.2 TS1M0 | 9.3 TS1M0 |
Microsoft Windows XP Professional | 9.2 TS1M0 | 9.3 TS1M0 |
Windows Vista | 9.2 TS1M0 | 9.3 TS1M0 |
Windows Vista for x64 | 9.2 TS1M0 | 9.3 TS1M0 |
64-bit Enabled AIX | 9.2 TS1M0 | 9.3 TS1M0 |
64-bit Enabled HP-UX | 9.2 TS1M0 | 9.3 TS1M0 |
64-bit Enabled Solaris | 9.2 TS1M0 | 9.3 TS1M0 |
HP-UX IPF | 9.2 TS1M0 | 9.3 TS1M0 |
Linux | 9.2 TS1M0 | 9.3 TS1M0 |
Linux for x64 | 9.2 TS1M0 | 9.3 TS1M0 |
OpenVMS on HP Integrity | 9.2 TS1M0 | 9.3 TS1M0 |
Solaris for x64 | 9.2 TS1M0 | 9.3 TS1M0 |
*
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.
Type: | Problem Note |
Priority: | high |
Topic: | Analytics ==> Analysis of Means SAS Reference ==> Procedures ==> TTEST
|
Date Modified: | 2011-03-21 12:56:43 |
Date Created: | 2011-03-16 10:23:19 |