PLACE: 319 Snedecor
SPEAKER: Lance A. Waller, Department of Biostatistics, Rollins School of Public Health, Emory University, Atlanta, GA
TITLE: Clusters and clustering in spatial point patterns: Applications involving sea turtle nesting and epidermal nerve fibers
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 anomoly 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?"
COFFEE: 3:45 p.m., 104 Snedecor Hall
Jeanette La Grange
Department of Statistics
102 Snedecor
Iowa State University
Ames, IA 50010-1210
515 294-3440 (office)
515 294-4040 (fax)