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Journal Article 
Applications of the Poly-K Statistical Test to Life-Time Cancer Bioassay Studies 
Gebregziabher, M; Hoel, D 
Human and Ecological Risk Assessment
ISSN: 1080-7039
EISSN: 1549-7860 
The statistical analysis of cancer bioassay data has historically depended on the pathological determination of the experimental animal's cause of death. The poly-k statistical test has provided a method of statistical analysis of animal bioassay data without the need for cause of death information. The test has been shown to have good statistical properties in the typical 2-year cancer bioassay. However, while the poly-k test has been applied to chronic lifetime animal studies, it has not been formally evaluated with respect to the operating characteristics of this statistical test when applied to such studies. Thus, our objective is to assess the performance of the poly-k test for lifetime studies and to make comparisons with other tests. We observed in one recent lifetime study of the gasoline additive MTBE that the application of the poly-k test was not statistically robust. Simulation studies were subsequently conducted for a limited number of scenarios of lifetime cancer bioassays. These simulations showed that the poly-k test is not statistically robust for testing effect of increasing dose in some lifetime cancer studies. 
logistic regression score test; logrank test; survival adjusted trend tests; type-I error; re-weighted poly-k test; power