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.
Background
The two-step floating catchment area (2SFCA) method is a special case of a
gravity 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 laws of gravity. Generally, the social science models contain some elements of mass and ...
of
spatial interaction that was developed to measure spatial accessibility to
primary care physician
A primary care physician (PCP) is a physician 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. The term ...
s.
[Luo and Wang 2003b] 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 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 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 (i.e. rural and urban).
The method has been applied to other related public health issues, such as access to healthy food retailers.
[Chen, 2017]
See also
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Primary care service area
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Gravity model of migration The gravity model of migration is a model in urban geography derived from Newton's law of gravity, and used to predict the degree of migration interaction between two places. Newton's law states that: "Any two bodies attract one another with a for ...
Notes
References
* Luo, W., Wang, F., 2003a. Spatial accessibility to primary care and physician shortage area designation: a case study in Illinois with GIS approaches. In: Skinner, R., Khan, O. (Eds.), ''Geographic Information Systems and Health Applications''. Idea Group Publishing, Hershey, PA, pp. 260–278.
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*Wang, F. 2006. Quantitative Methods and Applications in GIS. London: CRC Press.
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{{DEFAULTSORT:Two-Step Floating Catchment Area Method
Geostatistics
Accessibility
Urban studies and planning terminology