The approaches to measuring the potential spatial access to urban health services revisited: distance types and aggregation-error issues (2017)
AuthorsGelb J, Apparicio P, Dube A-S, Kingham SP, Gauvin L, Robitaille Eshow all
Background: The potential spatial access to urban health services is an important issue in health geography, spatial epidemiology and public health. Computing geographical accessibility measures for residential areas (e.g. census tracts) depends on a type of distance, a method of aggregation, and a measure of accessibility. The aim of this paper is to compare discrepancies in results for the geographical accessibility of health services computed using six distance types (Euclidean and Manhattan distances; shortest network time on foot, by bicycle, by public transit, and by car), four aggregation methods, and fourteen accessibility measures. Methods: To explore variations in results according to the six types of distance and the aggregation methods, cor‑ relation analyses are performed. To measure how the assessment of potential spatial access varies according to three parameters (type of distance, aggregation method, and accessibility measure), sensitivity analysis (SA) and uncertainty analysis (UA) are conducted. Results: First, independently of the type of distance used except for shortest network time by public transit, the results are globally similar (correlation >0.90). However, important local variations in correlation between Cartesian and the four shortest network time distances are observed, notably in suburban areas where Cartesian distances are less precise. Second, the choice of the aggregation method is also important: compared with the most accurate aggregation method, accessibility measures computed from census tract centroids, though not inaccurate, yield important measurement errors for 10% of census tracts. Third, the SA results show that the evaluation of potential geographic access may vary a great deal depending on the accessibility measure and, to a lesser degree, the type of distance and aggregation method. Fourth, the UA results clearly indicate areas of strong uncertainty in suburban areas, whereas central neighbourhoods show lower levels of uncertainty. Conclusion: In order to accurately assess potential geographic access to health services in urban areas, it is par‑ ticularly important to choose a precise type of distance and aggregation method. Then, depending on the research objectives, the choices of the type of network distance (according to the mode of transportation) and of a number of accessibility measures should be carefully considered and adequately justifed.
CitationGelb J, Apparicio P, Dube A-S, Kingham SP, Gauvin L, Robitaille (2017). The approaches to measuring the potential spatial access to urban health services revisited: distance types and aggregation-error issues. Angers, France: International Medical Geography Symposium. 03/07/2017-06/07/2017. International Journal of Health Geographics. 16. 1. 32-.
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KeywordsAccessibility of health services; GIS; Sensitivity analysis; Uncertainty analysis; Cartesian distance; Network distances
ANZSRC Fields of Research11 - Medical and Health Sciences::1117 - Public Health and Health Services::111708 - Health and Community Services
11 - Medical and Health Sciences::1117 - Public Health and Health Services::111706 - Epidemiology
16 - Studies in Human Society::1604 - Human Geography::160404 - Urban and Regional Studies (excl. Planning)
16 - Studies in Human Society::1604 - Human Geography::160499 - Human Geography not elsewhere classified