Seminars

General Departmental Seminar Series

Clusters and Clustering in Spatial Point Patterns: Applications Involving Sea Turtle Nesting and Epidermal Nerve Fibers

Lance A. Waller, Department of Biostatistics, Rollins School of Public Health, Emory University

Friday, April 15, 2005,12:00am-1:00pm,

3265 MSC

ABSTRACT

This presentation explores non-parametric statistical inference for spatial point patterns driven by two specific applications: the first investigates the impact of a fishing pier on nesting patterns of sea turtles on Juno Beach, Palm Beach County, Florida; and the second seeks to quantify the amount of "clustering" among epidermal nerve fibers (ENFs) in a 3mm skin biopsy. While the motivations differ widely in both substantive fields (conservation biology and neurology) and spatial scale (meters to microns), the underlying statistical questions build from basic first- and second-order properties of spatial point processes. A key issue is the difference between searching for evidence of a "cluster" (a local anomaly in the expected number of events per unit area) and searching for evidence of "clustering" (a general tendency for events to occur near other events). In both cases, we apply kernel-based estimation and Monte Carlo assessments of significance to address specific questions of interest, namely, "Does the fishing pier impact nesting patterns?" and "At what distances do ENFs tend
to cluster together?"

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