Key Equations
The following are some of the key equations (with plain English paraphrases) from his article in sociometry:
(Demographic Force = (population 1 multiplied by population 2) divided by (distance squared))
(Demographic Energy = (population 1, multiplied by population 2) divided by distance; this is also Zipf's determinant
(Demographic Potential of population at point 1 = population at point 2, divided by distance)
(Demographic Potential in general = population divided by distance, in persons per mile)
(Demographic Gradient = persons per (i.e. divided by) square mile)
The potential of population at any point is equivalent to the measure of proximity of people at that point (this also has relevance to Georgist economic rent theory Economic rent#Land rent).
For comparison, Reilly's retail gravity equilibrium (or Balance/Break Point) is paraphrased as:
(Population 1 divided by (distance to balance, squared) = Population 2 / (distance to balance, squared))
Read more about this topic: Demographic Gravitation
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