mathematics

Two-step floating catchment area method

Two-step floating catchment area method is a mathematics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Two-step floating catchment area method rather than just read about it. In short: 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.

Key takeaways

Two-step floating catchment area method belongs to mathematics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Two-step floating catchment area method to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Two-step floating catchment area method from memory before moving on to harder problems.

Reference excerpt

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 of spatial interaction that was developed to measure spatial accessibility to primary care physicians. 2SFCA is based on the accessibility measure developed by Shen (1998), who used it to compare accessibility to jobs among workers residing in different locations and traveling by different transportation means, and more generally, to measure accessibility to spatially distributed opportunities that have capacity limitations (i.e., rival goods). 2SFCA 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 (this interpretation is based on the mathematical proof by Shen (1998)). It is easy to implement in a GIS environment. In essence, applying the accessibility measure formulated by Shen (1998) the 2SFCA method is an automated procedure for measuring 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.

See also Primary care service area Gravity model of migration

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, Pennsylvania, pp. 260–278. Shen, Q. (1998). "Location characteristics of inner-city neighborhoods and employment accessibility of low-wage workers". Environment and Planning B: Planning and Design. 25 (3): 345–365. Bibcode:1998EnPlB..25..345S. doi:10.1068/b250345. Luo, W.; Wang, F. (2003b). "Measures of spatial accessibility to health care in a GIS environment: synthesis and a case study in the Chicago region" (PDF). Environment and Planning B: Planning and Design. 30 (6): 865–884. Bibcode:2003EnPlB..30..865L. doi:10.1068/b29120. PMC 8238135. PMID 34188345. Luo, W.; Qi, Y. (2009). "An enhanced two-step floating catchment area (E2SFCA) method for measuring spatial accessibility to primary care physicians" (PDF). Health & Place. 15 (4): 1100–1107. Bibcode:2009HePla..15.1100L. doi:10.1016/j.healthplace.2009.06.002. PMID 19576837. Radke, J.; Mu, L. (2000). "Spatial decomposition, modeling and mapping service regions to predict access to social programs". Geographic Information Sciences. 6 (2): 105–112. Bibcode:2000AnGIS...6..105R. doi:10.1080/10824000009480538. S2CID 33286600. Wang, F.; Luo, W. (2005). "Assessing spatial and nonspatial factors for healthcare access: towards an integrated approach to defining health professional shortage areas" (PDF). Health and Place. 11 (2): 131–146. doi:10.1016/j.healthplace.2004.02.003. PMID 15629681. Wang, F. 2006. Quantitative Methods and Applications in GIS. London: CRC Press. ISBN 0-8493-2795-4 McGrail, Matthew R.; Humphreys, John S. (2009). "Measuring spatial accessibility to primary care in rural areas: Improving the effectiveness of the two-step floating catchment area method". Applied Geography. 29 (4): 533–541. Bibcode:2009AppGe..29..533M. doi:10.1016/j.apgeog.2008.12.003. Chen, X. (2017). "Take the edge off: A hybrid geographic food access measure". Applied Geography. 87: 149–159. Bibcode:2017AppGe..87..149C. doi:10.1016/j.apgeog.2017.07.013.

Worked examples

Example 1 — a first encounter with Two-step floating catchment area method

Start with the simplest possible case. Write down what Two-step floating catchment area method claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Two-step floating catchment area method before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Two-step floating catchment area method ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Two-step floating catchment area method

In research: Two-step floating catchment area method appears in mathematics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Two-step floating catchment area method in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Two-step floating catchment area method is common in secondary-school and first-year university syllabi. It links to neighbouring topics Accessibility, Geostatistics, Urban studies and planning terminology, so understanding it makes those chapters shorter.
In everyday life: Look for Two-step floating catchment area method outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Two-step floating catchment area method in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Two-step floating catchment area method means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Two-step floating catchment area method out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Two-step floating catchment area method in simple terms?

Why does Two-step floating catchment area method matter?

Because it connects several mathematics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Two-step floating catchment area method?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Two-step floating catchment area method.