Plot I
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What are the consequences of spatially inaccessible financial institutions? Residents without access to banking services often do not have a savings account. They may be unable to access affordable credit to purchase a home, pay for higher education, or replace an older vehicle. When residents lack access to banking services they often turn to non-traditional forms of credit that charge high-interest rates and expensive fees.
Let’s have a look at the distribution of bank branches on top of the city’s census tracts.
Points in polygon
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In its most basic form, spatial accessibility factors in the supply of an amenity, the demand for that supply, and the distance facilitating or impeding the linkage between supply and demand. A simple approach to measuring spatial access is to count the number of amenities located within neighborhood boundaries. The number of banks represents the supply. Distance is captured by banks residing within tract boundaries. The demand can take on many forms, but one common proxy is the resident population size.
Point proximity buffers
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Another approach to measuring access is to capture distance from the nearest amenities. There are several ways to account for distance. One method involves counting the number of amenities within x miles of the neighborhood. The tract being mapped is located in the West Los Angeles area along the coast.
Distance to nearest bank
A common spatial accessibility measure is the distance to the closest amenity (e.g. nearest bank). It allows one to evaluate the immediate proximity to the bank. There are on average 6.9 banks within 1 mile of tracts in Los Angeles.
In contrast to the simple buffer method here presented, Floating Catchment Area (FCA) accounts for not just the number of amenities that fall inside the buffer, but also the centroids of other nearby tracts. The method accounts for competition for services among residents in other neighborhoods (competing demand). See next.
Two-step Floating Catchment Area
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The two-step Floating Catchment Area (2SFCA) method calculates catchment areas for both supplier and consumer. It takes into account access from the demand side (resident population) and from the service area of the supplier (bank). But, not every bank can be treated equally. One measure of bank capacity is the number of its deposits in dollars. This is measured by the amount of deposits in millions. The catchment area (like the buffer radius r) used here is 1609 meters, or one mile. Higher values of TSFCA equals greater spatial access.