A market area has a range and a threshold which are determining the
profitability of the economic activity generating it. The threshold
is the minimal market area an activity must have to stay in operation.
It represents the spatial threshold of profitability where spatial attributes
such as population density and income have an important influence in its assessment.
The range is the effective market area of an activity from which it
draws its customer base. On graph A, activity
p will be profitable since its threshold is inferior to its range
R(A). On graph B, activity p is not profitable because its range
is inferior to its threshold.