Study's methodology combines visual interpretation with statistical analysis to illustrate 4 million commuter flows
Geographers from Dartmouth College and the University of Sheffield provide new insight into the economic geography of commuter megaregions in the U.S., by using an empirical approach that combines visual interpretation with statistical analysis. The findings appear in "PLOS One" and shed light on an old geographic problem: how to divide space into coherent unit areas.
These emerging "megaregions" reflect the economic links woven by millions of commuters traveling to and from work each day. They map out complex networks in which economic systems, natural resources and infrastructure are linked. Understanding the way functional geographic connections cross over the existing borderlines of states and regions is vital for developing institutional forms that match the patterns of the contemporary world.
"We know just how interconnected people are across vast distances in the modern economy--that's one of the basic principles of globalization," says co-author Garrett Dash Nelson, a postdoctoral fellow in the department of Geography and the Society of Fellows at Dartmouth College. "But we still need bounded areal units for things like regional administration and transportation planning. Our paper offers a new way of thinking about how these economic flows and megaregional boundaries are related."
The study examines 4 million commuter flows based on Census Tract data from the Census Bureau's American Community Survey (ACS) 2006-2010. The Census Tract was selected as the spatial unit of measure given that with an average population of 4,000, this unit was geographically large enough to reflect a major number of employers.
The geographers applied two methodologies: a visual heuristic approach and an algorithmic approach, and explain the shortcomings of relying on one approach. For the visual heuristic approach, which is based on a trial and error method to produce results, the ACS data was filtered based on distance and flow volume thresholds until visually effective results were obtained. For this approach, 50 miles was used as the threshold to measure "long distance commutes." The visual approach enables an interpretive depiction of centers of employment and suburban flows; however, with no hard edges within the visual, it is difficult to determine where a functional commuter region or community may exist. This approach therefore requires subjective guesswork to determine regional edges.
The algorithmic approach tries to assign the census tracts or nodes into communities based on the number of commuters, using the Combo software developed at MIT's Senseable City Lab. The algorithm relies on the connectivity between nodes and does not take into consideration geographic proximity. This method can identify spatially contiguous areas that one would not ordinarily be able to determine visually. The algorithm is able to make judgement calls that one cannot make with a map.
Below are visuals from the study reflecting commutes to Minneapolis-St.Paul within a 50-mile radius based on the visual heuristic approach as compared to commutes within the Twin Cities region using the algorithmic approach. The map of the Twin Cities region illustrates the spatial connectivity or in this case, the functional commuter regions or communities, within the broader megaregion of which the largest part is Minneapolis-St. Paul.
The study highlights the complexity of accurately capturing spatial economic analyses and is a reminder that spatial data visualizations are subjective and are not value neutral. Moreover, it reinforces how megaregions and the functional regions that comprise them serve as another way to define community, demonstrating the role that economic geography can have in assessing the needs of our society.
Garrett Dash Nelson is available for comment at Garrett.G.D.Nelson@dartmouth.edu. In addition, co-author Alasdair Rae, senior lecturer in the department of Urban Studies and Planning at the University of Sheffield, is also available for comment at: email@example.com.
Amy D. Olson | EurekAlert!
Visual intelligence is not the same as IQ
09.11.2017 | Vanderbilt University
Amazingly flexible: Learning to read in your thirties profoundly transforms the brain
26.05.2017 | Max-Planck-Institut für Kognitions- und Neurowissenschaften
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
The Fraunhofer Institute for Laser Technology ILT and Rapid Shape GmbH are working together to further develop resin-based 3D printing. The new “TwoCure” process requires no support structures and is significantly more efficient and productive than conventional 3D printing techniques for plastic components. Experts from Fraunhofer ILT will be presenting the state-funded joint development that makes use of the interaction of light and cold in forming the components at formnext 2017 from November 14 to 17 in Frankfurt am Main.
Much like stereolithography, one of the best-known processes for printing 3D plastic components works using photolithographic light exposure that causes liquid...
30.10.2017 | Event News
23.10.2017 | Event News
17.10.2017 | Event News
10.11.2017 | Power and Electrical Engineering
10.11.2017 | Information Technology
10.11.2017 | Earth Sciences