Two-step floating catchment area (2SFCA) method
Encyclopedia
The two-step floating catchment area (2SFCA) method is a method for combining a number of related types of information into a single, immediately meaningful, index that allows comparisons to be made across different locations. Its importance lies in the improvement over considering the individual sources of information separately, where none on its own provides an adequate summary.
of spatial interaction that was developed to measure spatial accessibility to primary care physician
s. 2SFCA can also be used to measure other accessibility such as accessibility to jobs, to cancer care facilities, etc. It was inspired by the spatial decomposition idea first proposed by Radke and Mu (2000).
The 2SFCA method not only has most of the advantages of a gravity model, but is also intuitive to interpret, as it uses essentially a special form of physician-to-population ratio. It is easy to implement in a GIS
environment. In essence, the 2SFCA method measures spatial accessibility as a ratio of primary-care physicians to population, combining two steps:
It has been recently enhanced by considering distance decay
within catchments and called the enhanced two-step floating catchment area (E2SFCA) method.
Furthermore, the use of capping certain services according to nearby population size,can improve the accuracy when analyzing across areas of different environments (ie. rural and urban).
Background
The two-step floating catchment area (2SFCA) method is a special case of a gravity modelGravity model
Gravity models are used in various social sciences to predict and describe certain behaviors that mimic gravitational interaction as described in Isaac Newton's law of gravity...
of spatial interaction that was developed to measure spatial accessibility to primary care physician
Primary care physician
A primary care physician, or PCP, is a physician/medical doctor who provides both the first contact for a person with an undiagnosed health concern as well as continuing care of varied medical conditions, not limited by cause, organ system, or diagnosis....
s. 2SFCA can also be used to measure other accessibility such as accessibility to jobs, to cancer care facilities, etc. It was inspired by the spatial decomposition idea first proposed by Radke and Mu (2000).
The 2SFCA method not only has most of the advantages of a gravity model, but is also intuitive to interpret, as it uses essentially a special form of physician-to-population ratio. It is easy to implement in a GIS
Geographic Information System
A geographic information system, geographical information science, or geospatial information studies is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographically referenced data...
environment. In essence, the 2SFCA method measures spatial accessibility as a ratio of primary-care physicians to population, combining two steps:
- it first assesses “physician availability” at the physicians' (supply) locations as the ratio of physicians to their surrounding population (i.e., within a threshold travel time from the physicians)
- it sums up the ratios (i.e., physician availability derived in the first step) around (i.e., within the same threshold travel time from) each residential (demand) location.
It has been recently enhanced by considering distance decay
Distance decay
Distance decay is a geographical term which describes the effect of distance on cultural or spatial interactions. The distance decay effect states that the interaction between two locales declines as the distance between them increases...
within catchments and called the enhanced two-step floating catchment area (E2SFCA) method.
Furthermore, the use of capping certain services according to nearby population size,can improve the accuracy when analyzing across areas of different environments (ie. rural and urban).