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 probabilities line, unless there are no other alternative locations. The indifference point becomes the point of equal probability that a customer will patronize one location or another.
In the above figure, a customer has a greater chance (0.71) to patronize location A at the midpoint than location B (0.29). The advantage of Huff’s retail model is that it leaves room for customer choice.