Gravity Model Macro

The Gravity Model Macro is an iterative macro that takes each demand pull and associates a particular Gravity Value to it based on given supply to produce a Gravity for each Demand ID and create the demand surface. A minimum relevant distance, frictional movement exponent and Null Competitor Distance can be specified. You can also select to Filter on Demand Farther than 2x Null competitor distance, choose to use a Null Competitor or return the full detail of the iterative values.  

Definition of Terms

Friction of Movement: The effect of distance on the interaction between origin and destination zones. Friction of Movement parameters include: terms of cost, time spent on commuting between origin and destination zones, multidimensional measures combining time, money, and effort spent in commuting between zones, (b) the values of the exponent of the distance function, known also as the "distance decay parameter" – which varies with the purpose of the interaction (e.g. trip purpose) as well as with distance itself and (c) the use of other functional forms of the distance function.

Null Competitor Distance: the distance at which most locations (fixed, potential and competitor) see business decline substantially. In general, this may be thought of the distance at which 50% of customers will decide on other means to fulfill their objective - if the store is X miles away, they may buy mail order, purchase online, or buy and alternative product.