SUPPORT / SAMPLES & SAS NOTES
Problem Note 36040: Incorrect OUTPUT statement variables for zero-inflated Poisson (ZIP) models using full-rank parameterization
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If you fit a zero-inflated Poisson (ZIP) model in PROC GENMOD and one or more predictors in the model are CLASS variables with parameterization other than the default (PARAM=GLM), then the zero inflation probability is computed incorrectly. As a result, values of PZERO=, PRED=, RESRAW=, and RESCHI= variables in the OUTPUT statement are incorrect. The model parameters, their tests, and the model fit criteria are correct.
To avoid the problem, use the default parameterization by either omitting the PARAM= option(s) in the CLASS statement, or specify PARAM=GLM.
Operating System and Release Information
| Product Family | Product | System | SAS Release | |
| Reported | Fixed* | |||
| SAS System | SAS/STAT | z/OS | 9.2 TS1M0 | 9.2 TS2M2 |
| Microsoft® Windows® for 64-Bit Itanium-based Systems | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Datacenter 64-bit Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Enterprise 64-bit Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows XP 64-bit Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft® Windows® for x64 | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Datacenter Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Enterprise Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows Server 2003 Standard Edition | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Microsoft Windows XP Professional | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Windows Vista | 9.2 TS1M0 | 9.2 TS2M2 | ||
| 64-bit Enabled AIX | 9.2 TS1M0 | 9.2 TS2M2 | ||
| 64-bit Enabled HP-UX | 9.2 TS1M0 | 9.2 TS2M2 | ||
| 64-bit Enabled Solaris | 9.2 TS1M0 | 9.2 TS2M2 | ||
| HP-UX IPF | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Linux | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Linux for x64 | 9.2 TS1M0 | 9.2 TS2M2 | ||
| OpenVMS on HP Integrity | 9.2 TS1M0 | 9.2 TS2M2 | ||
| Solaris for x64 | 9.2 TS1M0 | 9.2 TS2M2 | ||