Here are some major results obtained in this research project during the past year: Microarray gene expression studies over ordered categories are routinely conducted to gain insights into biological functions of genes and the underlying biological processes. Some common experiments are time-course/dose-response experiments where a tissue or cell-line is exposed for different doses and/or durations of time to a chemical. A goal of such studies is to identify gene expression patterns/profiles over the ordered categories. In some instances data across ordered groups are correlated, for example when repeated measurements are taken over the same subject over time. In this research program we developed methodology that accounts for such correlations. Researchers routinely use historical control data (HCD) when analyzing rodent carcinogenicity data obtained in a particular study. Although the concurrent control group is considered to be the most relevant group to compare with the dose groups, the HCD provides a broader perspective to assist in understanding the significance of the current study. The HCD is used to provide information about the incidences of spontaneous tumors and malignant systemic disorders such as lymphoma and leukemia. In this research program we developed a simple statistical methodology that can be used for comparing the tumor response in the current control group with that of the historical controls. We demonstrate that the commonly used historical range based methodology can result in an unacceptably high false positive rate whereas the proposed method controls the false positive rate at the desired nominal level.
Showing the most recent 10 out of 26 publications
