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Statistical Programs
College of Agriculture
and Life Sciences
University of Idaho
Seminar Announcement
"Applied Statistics in Agriculture"
Properties of a Stochastic Logistic Equation

Presented By
Dr. Brian C. Dennis
Department of Fish and Wildlife Resources
and
Department of Statistics
University of Idaho

Tuesday, November 9
3:30 P. M.
Ag. Science 62

     The logistic population growth equation appears in virtually every ecology textbook. Yet, it has the reputation of being a "toy model" intended as a simple teaching concept, but not intended for describing real population systems. In this presentation, I argue that adding one ingredient --stochasticity-- transforms the model into a frequently useful data analysis tool.

     The resulting model, of logistic growth with environmental-type noise, is a stochastic process known as a diffusion process. The concept of carrying capacity is no longer a point equilibrium, but rather is a gamma probability distribution. Many statistical properties of the model can be derived as formulas. I explore various approximation schemes for the full time-dependent probability distribution of the process; the schemes are helpful for fitting the model to time series data. Various examples that use the model for statistical analysis of population time series are developed.


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