A Geographic Information System (GIS) is the high-tech equivalent of a map. Unlike traditional paper maps, which are usually made to fit a single purpose and, once printed, go out of date fairly quickly, a GIS may be used for any number of different purposes and may combine countless sources of data that can be manipulated and updated at any time.
A GIS is a computerized tool used to map and analyze the spatial relationships between the earth’s features and events. A typical GIS set-up includes a high-powered computer, specialized mapping software and one or more digital databases containing information about a particular feature or event along with geographic information about where that feature or event is located on the earth. An informative presentation on geographic information systems is available at the U.S. Geological Survey (USGS) website.
Using a GIS, researchers can relate otherwise disparate data on the basis of common geography, creating new information from existing data resources. “Hidden” in most data is a geographic component: an address, postal code, census block, city, county or latitude/longitude coordinate. GIS software allows researchers to explore and analyze data by location, revealing patterns, relationships and trends that are not readily apparent in the text of the data itself.
For example, a GIS can be used to map where people diagnosed with a particular disease live. A good example of using GIS for this type of research is illustrated by the National Cancer Institute’s GIS website. Mapping diseases can help epidemiologists recognize disease trends or outbreaks. Additionally, a GIS can be used to overlay the locations of people diagnosed with a disease with the locations of possible causes of that disease. GIS technology, used in conjunction with rigorous epidemiologic analyses, can help epidemiologists to link together diseases and their causes.
This is the application for which the Environmental Health Investigations Branch (EHIB) has developed its Geographic Information System. With its GIS, EHIB has analyzed data on environmental exposures, such as automobile traffic, pesticides and drinking water, and human health outcomes, such as cancer and respiratory problems. EHIB maintains GIS workstations that enable its staff of specialists to map and analyze spatial correlates of case and exposure data. EHIB's GIS provides access to and utilization of a wide range of digital geographic data from both commercial vendors and public domains including Federal, State and University organizations.
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