Spatial Association and Dissociation

Suppose there are two sets of data, each sampled at the same spatially-referenced units.
They might represent two species sampled simultaneously.

Typical questions might be: do the two species occur close together in similar habitats,
or are they segregated from one another? These questions concern their spatial association.

If individuals of the two different species attract with affirmative interactions we might
expect positive spatial association. If they inhibit each other, with repulsive interactions,
then negative spatial dissociation may result.

                  Attraction, of red                                                  Repulsion, of red
                  individuals to blue                                                individuals from blue
                  individuals, generates                                          individuals, generates
                  positive association                                              negative dissociation