השוואת שיטות

	Two-Step Floating Catchment Area	Catchment Area Analysis
תחום	Human Geography	Human Geography
משפחה	Process / pipeline	Process / pipeline
שנת המקור	2003	1964
הוגה השיטה	Wei Luo & Fahui Wang	David L. Huff (probabilistic formulation)
סוג	Spatial accessibility measure for competition over constrained services	Delineation of the geographic area served by a facility
מקור מכונן	Luo, W., & Wang, F. (2003). Measures of spatial accessibility to health care in a GIS environment: synthesis and a case study in the Chicago region. Environment and Planning B: Planning and Design, 30(6), 865–884.	Huff, D. L. (1964). Defining and estimating a trading area. Journal of Marketing, 28(3), 34–38.
כינויים	2SFCA, Floating Catchment Area Method, Enhanced Two-Step Floating Catchment Area, 2SFCA Accessibility	Trade Area Analysis, Service Area Delineation, Market Area Analysis, Catchment Delineation
קשורות	4	4
תקציר	The two-step floating catchment area (2SFCA) method measures spatial accessibility to constrained services — most famously physicians and hospitals — by accounting not only for how close supply is but for how many other people are competing for it. Introduced by Wei Luo and Fahui Wang in 2003, it works in two passes: first computing a supply-to-demand ratio at every service location, then summing those ratios over all services within reach of each population site. The result is a single accessibility score per location that captures both proximity and crowding, and it has become the standard measure of access to healthcare and other capacity-limited services.	Catchment area analysis delineates the geographic area that a facility — a shop, hospital, school, or station — actually serves, turning the abstract question of 'who uses this place?' into a mapped polygon. Methods range from the simplest fixed-radius buffer through nearest-facility (Voronoi) tessellation and network drive-time isochrones to David Huff's 1964 probabilistic model, in which patronage is shared among competing facilities by their relative attractiveness and distance. The choice of method reflects how strictly customers are tied to the nearest centre and how much competition and travel cost shape real behaviour.