Oregon State University

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Department of Statistics Research Seminar

Modeling density dependence in population growth rates

Monday, February 4, 2013 3:55 PM - 5:00 PM

Quinn Payton, PhD Candidate, Oregon State University

The modeling of growth in ecological populations is a fundamental concept in academic research and wildlife management efforts. A population's growth rate is determined by both birth and immigration, while the population's loss rate is primarily driven by death and emigration. Density dependence refers to the relationship in a population between its size and its gain and loss rates. When the magnitude and direction of these rates of change are influenced directly by the population size, they are considered density-dependent.

Researchers often attempt to assess density dependence based on annual estimates of population size. The small sizes of such datasets have led many researchers to abandon complex modeling approaches and instead attempt nonparametric statistical analyses. The shortcomings and biases of these approaches have been detailed in various papers.

Parametric alternatives have started to come back into favor. One of the more recent and robust of these parametric methods is based on the Gompertz State-Space model, in which maximum likelihood estimation and parametric bootstrapping are used to identify and quantify density dependence. I will present problems that arise when using these methods along with some suggested remedies.


Bexell Hall (campus map)
207
Free
Judith Burks
541-737-3883
judy.burks at oregonstate.edu
College of Science, Statistics Department