Huff's Law
Huff's retail model (1963) assumes that customers have a choice to patronize a location in view of other alternatives. Thus, a market area is expressed as a continuous line of probabilities, unless there are no other alternative locations. The point of indifference becomes the point of equal probability that a customer will patronize one location or another. On the above figure, a customer has a greater chance (0.71) to patronize location A at the mid point than patronize location B (0.29). The advantage of Huff's retail model is that it leaves room for customer choice.