GGR252H1 Lecture Notes - Lecture 7: Geocoding, Distance Decay
Document Summary
This simple gravity model is a modification of reilly"s law of retail gravitation. Two cities attract trade from an intermediate town in the vicinity of the breaking point approximately in direct proportion to the populations of the two cities and in inverse proportion to the squares of the distances. Formulas do not need to be memorized for the exam. The converse formula (see below) requires data on distance between centre. Together these two variables are thought to adequately measure the relative utility of the centres. The formula suggests that the utility of the centre decreases. Unlike the theissen polygon, the converse method does not assume that all centers are equal in attractiveness (size) Both these models (thiessen and converse) are trying to have a crisp dividing line. spatial monopoly. Casts reillys law of retail gravitation of probabilistic framework. To apply the model we need; measure of size, measure of accessibility.
