Issues to Consider Before Initiating a Project in Medical Geography.

Abstract

This article is directed toward health professionals who have a limited background in epidemiology and geography but are interested in medical geography. Although geospatial analysis and the availability of geographic information systems is a growing field, there is little literature available regarding medical geography. Medical geography is a field that incorporates geographical and epidemiological concepts in order to investigate relationships between health and location (1). This article will be an introduction to the fundamental issues, including errors and biases, often encountered in geography and epidemiology, which inherently occur in medical geography. All issues should be considered prior to initiating a project in medical geography. Projects in medical geography utilize spatially associated data, along with a number of different analytical techniques to investigate topics of interest. These techniques are applied in order to make assumptions about relationships or interactions within spatial data (2). Three core elements of spatial analysis are cartography, data mining, and mathematical modeling (2). Often approached in the aforementioned order, cartography is utilized first to create a map on which the results can be visualized. Once a foundation has been made, data mining attempts to reveal relationships within the data to develop a better understanding of potential outcomes that could result from the data (2). Finally, once relationships have been identified, mathematical models can be applied to the data, in order to analyze and interpret results, proposing potential answers to questions previously hypothesized (2). Two locational data forms are used in cartography: raster data and vector data. Both can be utilized in spatial analysis; however, each format has its own advantages. When dealing with raster data, the area of space that is being investigated is divided up into a number of equally sized cells or pixels, all of which can be individually classified according to the factor(s) being investigated (e.g., temperature) (3). On the one hand, raster data represent points using a single cell and lines using a number of adjacent cells and shapes using a region of cells (4). On the other hand, vector data represent data as points, lines, and polygons (3). Points are used to represent small features, lines represent long features of small width, and polygons represent features of a given area (4). There are also two forms of attribute data used in spatial analysis: point data and regional data. Point data describe variables that are associated with a specific location, often denoted by x and y coordinates (5); whereas, regional data are associated with a defined area (5). Again, each type of attribute data has its own set of advantages and disadvantages. Vector, raster, point, and regional data can be used individually or in combination, depending on what is being investigated and the desired outcome. In medical geography, there is a natural relationship between data points that are within a certain distance from each other. The first law of geography, defined by Waldo Tobler is “Everything is related to everything else, but near things are more related than distant things” (6). Simply put, data points that are close together are more alike than those further apart. This phenomenon occurs frequently in medical geography since we are dealing with factors that are related to space. From this, it is important to be aware of possible exposure to errors and biases throughout your project. If errors and biases are incorporated into a data set, they may promote conclusions that are inaccurate, resulting in wasted time and resources.