Mapping health events - a comparison of approaches

Abstract

The Waikato Regional Public Health Unit (New Zealand) collects and maintains a database of notified health events that includes communicable diseases. This database can be used by health protection officers to identify problem areas that have unusually high incidences of events. Resources can then be targeted and officers can respond accordingly. However, for this data to be useful it needs to be represented as a rate of health events per 100,000 people. This paper investigates the use of Geographic Information Systems (GIS) to visualize and represent these data. Standard vector representations that use census area units are compared with raster representations that use focal neighbourhood functions. The two techniques produce rates of health events that differ by up to 100 per cent for a given location and scale. The vector technique is the standard approach and is easily understood. The raster technique enables more control over the scale of analysis and can provide a more spatially accurate representation of health events. If two techniques can produce such large differences in analysis results, it is important that health protection officers and epidemiologists give special consideration to the representation technique used. © 2001, Sage Publications. All rights reserved.