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Testing Spatial Segregation Using a Nearest-Neighbor Contingency Table
Ecology (1994)
  • Philip Dixon, University of Georgia
Segregation of species occurs when a species tends to be found near conspecifics.
This is frequently investigated using a contingency table, classifying each point
by its species and the species of its nearest neighbor. Pielou proposed using a 1-df chisquare
test of independence as a test of segregation. This test is inappropriate if all locations
within a study area are mapped. For completely mapped data, I derive the expectations
and variances of the cell counts in the nearest-neighbor contingency table under the null
hypothesis that species labels are randomly assigned to points. The properties of the cell
counts suggest a new 2-df chi-square test of spatial segregation, a pair of species-specific
tests, and a pair of species-specific measures of segregation. In small samples, the proposed
tests have the appropriate size, unlike the Pielou test. The new test is illustrated with three
examples: Pielou's Douglas-fir/ponderosa pine data, a realization of a mother-daughter
process, and the locations of male and female water tupelo trees.
  • nearest neighbor,
  • Pielou test,
  • segregation,
  • spatial pattern
Publication Date
Publisher Statement
This is an article from Ecology 75 (1994): 1940, doi:10.2307/1941598
Posted with permission. Copyright 1994 by the Ecological Society of America
Citation Information
Philip Dixon. "Testing Spatial Segregation Using a Nearest-Neighbor Contingency Table" Ecology Vol. 75 Iss. 7 (1994) p. 1940 - 1948
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