There are many things that a GIS can do better than other types of information system, there are some things that only a GIS can do. Location-Allocation modeling is unique to GIS; it enables organisations to decide where to place facilities, any facilities, such that they service the maximum demand.
The mantra of “location, location, location” is based on the truth that often where you decide to place your retail outlet, warehouse, hospital, police station, school or health centre will determine how accessible it is relative to the demand for the service it provides and therefore ultimately how successful it is. In the private sector businesses can succeed or fail on the basis of location. Similarly in the public sector the success of service provision can often be determined by location.
Target Market Share chooses the minimum number of facilities necessary to capture a specific percentage of the total market share in the presence of competitors. The total market share is the sum of all demand weight for valid demand points. You set the percent of the market share you want to reach and let the solver choose the fewest number of facilities necessary to meet that threshold.
Given facilities that provide goods and services and a set of demand points that consume them, the goal of location-allocation is to locate the facilities in a way that supplies the demand points most efficiently. As the name suggests, location-allocation is a twofold problem that simultaneously locates facilities and allocates demand points to the facilities.
ArcGIS is unique in the market in providing a set of analysis tools to address Location – Allocation problems, including;
- Minimise Impedance - reduces the overall distance the public needs to travel to reach the chosen facilities, useful for locating some public-sector facilities such as libraries, regional airports, museums, department of motor vehicles offices, and health clinics.
- Maximize Coverage - is frequently used to locate fire stations, police stations, and ERS centers, because emergency services are often required to arrive at all demand points within a specified response time. This algorithm can be equally important to private sector service providers.
- Minimize Facilities - the same as Maximize Coverage but with the exception of the number of facilities to locate, is constrained. This is especially relevant in the current economic climate where there is minimum capital available to invest in facilities.
- Maximize Attendance - assumes that the farther people have to travel to reach your facility, the less likely they are to use it. This is reflected in how the amount of demand allocated to facilities diminishes with distance. Useful for retail output location where competition is not a prevalent factor.
- Maximise Market Share – locates a specific number of facilities such that the allocated demand is maximized in the presence of competitors. The goal is to capture as much of the total market share as possible with a given number of facilities, which you specify. The total market share is the sum of all demand weight for valid demand points.
- Target Market Share - locates the minimum number of facilities necessary to capture a specific percentage of the total market share in the presence of competitors. You set the percent of the market share you want to reach and let the solver choose the fewest number of facilities necessary to meet that threshold.
ESRI Ireland has worked with the following organisations to help them analyse and solve Location-Allocation problems;