Distance Decay

Distance decay is a major cornerstone of spatial-temporal analysis and, hence, geography. Essentially, it states that the nearer two locales are, the greater is the expected attraction/interaction between the two and, conversely, the greater the distance is between two locales, the less the expected interaction. This seemingly commonsense notion has been restated as a formulation of spatial autocorrelation by the geographer Waldo Tobler. It has come to be known as Tobler's “first law of geography,” which states that “everything is related to everything else, but near things are more related than distant things.”

In its simplest form, the distance decay function can be portrayed graphically as a concave curve descending from the y axis, representing the intensity of a phenomenon, and extending along the x axis, ...