Part II covers methods for exploratory data analysis, starting in this chapter with the fundamental concept of the intensity of a point process.
A wildlife ecologist who maps bird nests in a survey might choose to report the result as an average density of nests per hectare. Dividing the total number of points by the area of the survey region gives the average density of points per unit area. In different contexts, the average number of points per unit area could be a measure of abundance (for example, the abundance of virus particles on a cell surface), density (of light-sensitive cells in the retina), productivity (of crops), risk (of crimes), intensity (of a lightning storm), or prospectivity (of undiscovered mineral deposits). The standard generic term is intensity.