For retailers the two basic functional uses of GIS are market profiling and location analysis. Marketing requires a detailed breakdown of the socio-economic and demographic status of immediate locales, the surrounding population, and subsequent estimation of the geographic market range. A market area is the geographic area from which a library draws most of its users. Maps based upon US geographic and political boundaries are provided to illustrate these concepts. Assigning each library branch a certain number of census tracts or block groups.
Block groups are smaller divisions within a census tract.
These can vary from country to country, e.g., Scotland population districts are called cachement grids. Determining branch markets by assigning equal portions of the population to the nearest existing facility. This is a modeling technique, location allocation which simply assigns each member of the population to the nearest facility. Determine a branch market by assigning a certain mile radii to be served. This is a standard and more general approach used to compare key features.