Comparing the Performances of Diggle's Tests of Spatial Randomness for Small Samples with and without Edge‐Effect Correction: Application to Ecological Data

Abstract

Diggle's tests of spatial randomness based on empirical distributions of interpoint distances can be performed with and without edge-effect correction. We present here numerical results illustrating that tests without the edge-effect correction proposed by Diggle (1979, Biometrics 35, 87-101) have a higher power for small sample sizes than those with correction. Ignoring the correction enables detection of departure from spatial randomness with smaller samples (down to 10 points vs. 30 points for the tests with correction). These results are confirmed by an example with ecological data consisting of maps of two species of trees in a West African savanna. Tree numbers per species per map were often less than 20. For one of the species, for which maps strongly suggest an aggregated pattern, tests without edge-effect correction enabled rejection of the null hypothesis on three plots out of five vs. on only one for the tests with correction.

Structure, Long-Term Dynamics, and Demography of the Tree Community

“…The patterns presented here have been inferred from works by Gignoux et al [37,40] on Crossopteryx febrifuga, Piliostigma thonningii , Cussonia arborea, and Bridelia ferruginea, on a detailed study of Borassus aethiopum populations [11], and on original results (Tables 18.2 and 18.3). Results presented here concern plots of Andropogoneae savanna with different tree densities.…”

Spatial Point Pattern Analysis of Human Settlements and Geographical Associations in Eastern Coastal China — A Case Study

“…There are three broad classes of second order point processes. The first is called complete spatial randomness (CSR) [52,53,54], in which points are independent of each other and the objects are distributed as a result of random chance. The second is called a cluster process, in which points are associated with each other and objects follow a certain process of concentration.…”

Improving the Integration of Coppice Forest Protection in Rockfall Model

“…Plusieurs méthodes permettant de corriger les "e ets de bords" sont comparées dans [Ripley, 1991,Gignoux et al, 1999. Deux méthodes semblent plus adaptées à K(r) et permettent d'obtenir un estimateur non biaisé quelque soit le domaine d'étude.…”