
8 Spatial Point Patterns: Methodology and Applications with R
Figure 1.9. Bronze particles in a filter, observed in long itudinal plane section, 18×7 mm. (R. Bern-
hardt, H . Wendrock; kindly contributed by U. Hahn.)
1.1.4 C ovariates
Our dataset may also include covariates — any data that we trea t as explanatory, rather tha n as part
of the ‘respon se’.
One type of covariate is a spatial function Z(u) defined at all spatial locations u. Figure 1.10
shows the locatio ns of 360 5 trees in a tropical ra inforest, with a supplementary map of the terrain
elevation (altitude) sh own in the background. The covariate Z(u) is the altitude at location ...