The Extension of the Vitality Model and Its Application

This is to certify that I have examined this copy of a master's thesis by Ting Li and have found that it is complete and satisfactory in all respects, and that any and all revisions required by the final examining committee have been made. Date:__________________________________ In presenting this thesis in partial fulfillment of the requirements for a master's degree at the University of Washington, I agree that the Library shall make its copies freely available for inspection. I further agree that extensive copying of this thesis is allowable only for scholarly purposes, consistent with " fair use " as prescribed in the U.S. Copyright Law. Any other reproduction for any purposes or by any means shall not be allowed without my written permission. Abstract The Extension of the Vitality Model and Its Application) developed a model of vitality to characterize the properties of survival system. In this thesis, I extend to Anderson's vitality model by adding initial distribution to vitality, which makes the model more realistic. A Gaussian and gamma initial distribution are discussed here. A new algorithm for estimating parameters based on simulated annealing is presented, which allows us to explore the properties of population through their vitality parameters. Comparisons of the refined model and Anderson's model based both on simulation and real animal survival data leads to an issue of model selection. Finally, the model is applied to human survival data, leading to insights related to survival improvement and mortality plateau. Figure Number Page Figure 1: Depicts individual vitality trajectories (eq. (1)) and survival (eq.