Gravity Model

This model is for predicting how much interaction there is between two different places; so, looking at the model to the right, you take the population of the first place and multiply it by the population of the second place. Then, you divide the that by the distance squared between the two places.

In other words:

population1 = population (number of people) in first place/area
population2 = population (number of people) in second place/area
distance2 = distance squared between the two places

This model/equation can be used to find how much traffic and migration there is between two areas. Also, can be used to kind of see how much trade there is, because of the amount of interaction.

Example: City #1 has a population of 100 people, and City #2 has a population of 300 people. The distance between City #1 and City #2 is 10 miles. So, after doing the math, you get 300.

A criticism is that things have changed it, such as space-time compression. People and places can be more connected even if they're farther away. So, this model will not always work.