Measuring Potential Spatial Access to Primary Health Care Physicians Using a Modified Gravity Model

Canadian Geographer / Le Géographe canadien, Volume 54 Issue 1, Pages 29 – 45, March 2010


“Ensuring equity of access to primary health care (PHC) across Canada is a continuing challenge, especially in rural and remote regions. Despite considerable attention recently by the World Health Organization, Health Canada and other health policy bodies, there has been no nation-wide study of potential (versus realized) spatial access to PHC. This knowledge gap is partly attributable to the difficulty of conducting the analysis required to accurately measure and represent spatial access to PHC. The traditional epidemiological method uses a simple ratio of PHC physicians to the denominator population to measure geographical access. We argue, however, that this measure fails to capture relative access. For instance, a person who lives 90 minutes from the nearest PHC physician is unlikely to be as well cared for as the individual who lives more proximate and potentially has a range of choice with respect to PHC providers. In this article, we discuss spatial analytical techniques to measure potential spatial access. We consider the relative merits of kernel density estimation and a gravity model. Ultimately, a modified version of the gravity model is developed for this article and used to calculate potential spatial access to PHC physicians in the Canadian province of Nova Scotia. This model incorporates a distance decay function that better represents relative spatial access to PHC. The results of the modified gravity model demonstrate greater nuance with respect to potential access scores. While variability in access to PHC physicians across the test province of Nova Scotia is evident, the gravity model better accounts for real access by assuming that people can travel across artificial census boundaries. We argue that this is an important innovation in measuring potential spatial access to PHC physicians in Canada. It contributes more broadly to assessing the success of policy mandates to enhance the equitability of PHC provisioning in Canadian provinces.”

Biodiverse: A Tool for the Spatial Analysis of Diversity

“Biodiverse is a tool for the spatial analysis of diversity using indices based on taxonomic, phylogenetic and matrix-based (e.g. genetic distance) relationships, as well as related environmental and temporal variations.

“Biodiverse supports four processes:

  1. linked visualisation of data distributions in geographic, taxonomic, phylogenetic and matrix spaces;
  2. spatial moving window analyses including richness, endemism, phylogenetic diversity and beta diversity;
  3. spatially constrained agglomerative cluster analyses; and
  4. randomisations for hypothesis testing.”

Jack Dangermond Explains the Need for GeoDesign

In the January/February 2010 issue of GEO Informatics magazine, editor Eric van Rees interviewed Jack Dangermond.  The last question in the interview covers the concept of GeoDesign.

“Eric van Rees: Can you please tell me something about the GeoDesign Concept?

“Jack Dangermond: My original field of study was landscape architecture and that is probably the mother profession of GeoDesign. GeoDesign is about integrating design with geographic and science-based information. In the early days of ESRI, I always expected that people would apply GIS to design-based problem solving and finding the best location for something. I have been a little disappointed that didn’t happen as rapidly or as naturally as I thought it would. My motivation for emphasizing it in the last year has been in part to make people aware that there’s a huge opportunity to move in this direction to make a better world. I also found that there have been tools missing in GIS, so we’ve been developing new software capabilities that support the GeoDesign process.

“In January we will host the first GeoDesign Summit. It will bring people from both the GIS and design fields together and have them share their work and get a conversation going. I’m not totally sure what the outcome is going to be, but I’m hoping a new profession or direction will emerge. I think we need this kind of mixing at this point to bring these two fields together; people who design the world with people who design the future. Today, geography lives very well in its world and designers live very well in their world, but there’s not this cross-mixing. I believe the outcome will be much enlightened ways to do development; ways that bring science into how we design things: cities, the environment, highways, everything that we do. Today we certainly see the need for this all the way from global warming to designing more livable and sustainable cities. We need more geographic thinking in the way we make decisions. GeoDesign is an attempt to try to do something about that.”