ABSTRACT
This chapter introduces the important spatial concepts relating to points whose spatial location is considered to be random. It discusses the general concept of a point pattern, of complete spatial randomness and the ideas of cluster and inhibitory point patterns. The basic key concept, which represents the starting point for the analysis of any spatial point pattern, is the hypothesis of complete spatial randomness. Two of the main classes of models that generate aggregated point patterns are the inhomogeneous Poisson processes, leading to apparent contagion, and the Poisson cluster processes, leading to true contagion. A class of point processes that describe aggregated point patterns due to apparent contagion is the class of inhomogeneous Poisson processes which can be simply defined by replacing the constant first-order intensity of the homogeneous Poisson point process with a non-negative function that varies on space.
