GGR 252 Lecture 7
Course breakpoint method
This simple gravity model is a modification of Reilly’s law of retail gravitation.
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