E2SFCA (Enhanced Two Steps Floating Catchment Area)

The Enhanced Two-Step Floating Catchment Area (E2SFCA) method is an advanced spatial accessibility measure used to evaluate the availability and accessibility of services, such as healthcare, relative to a population. Building on the basic 2SFCA method, E2SFCA incorporates distance decay effects, acknowledging that the influence of supply diminishes with increasing distance. The method involves two main steps: first, it calculates a supply-to-demand ratio at each service location by considering the surrounding population within a defined catchment area, applying a distance decay function to weight closer populations more heavily. In the second step, it aggregates these ratios at each population location by summing the weighted supply-to-demand ratios from all service locations within the population’s catchment area. This refined approach provides a more nuanced assessment of spatial accessibility, accounting for the varying impacts of distance on service availability.