Using GIS: When a Map is Worth a Thousand Words

Published on
October 2, 2008

John Snow had the right idea more than 150 years ago as he investigated the cause of a cholera epidemic in London.

Snow, a physician, sketched a map of his Soho neighborhood streets, water pumps and cholera deaths. When he finished, he saw a large clump of dots – each representing one person killed by cholera – near the Broad Street public water pump. Snow's celebrated map helped confirm that contaminated water in that pump had killed many Londoners who drank from it.

Today, some enterprising journalists are following in Snow's footsteps with a modern twist: They're using geographic information software (GIS) to map data for stories and graphics about toxic health threats, prescription medicine abuse and EMS response times.

Some examples:

• The Dallas Morning News used GIS for its June 2008 "Toxic Neighbors" series, which showed how dozens of hazardous chemical sites threatened the health of tens of thousands of Dallas County residents. The Morning News mapped some 900 chemical sites from local, state and federal agencies, and found the ones that were closest to schools and apartment buildings. The newspaper created an online Google Map, which showed the locations of the 52 plants that pose the most potential danger.

• The Lexington Herald-Leader used GIS in 2003 for its look at narcotics abuse in eastern Kentucky. Reporters working on the stories had heard that areas with high rates of legal narcotics prescriptions often have high rates of narcotics abuse. One of the journalists obtained data from the U.S. Drug Enforcement Administration documenting the number of prescriptions by county. She then combined that with U.S. Census population data and calculated legal prescription drug rates by county. Then she put it in a map, which made it clear that four of the top seven counties for narcotics prescriptions were in eastern Kentucky.

• The Arizona Daily Star also used GIS in 2003 to map emergency medical service call data. The newspaper found that more than half of the time, the city's own ambulances failed to reach the scene in less than eight minutes. Also, the mapping showed that the private ambulances that served the less developed parts of the city sometimes took up to 15 minutes to arrive.

Andrew aftermath coverage boosted GIS use

GIS mapping in journalism started in the early 1990s, with just a handful of journalists using the programs to help readers visualize demographic data from the 1990 Census. Then, in 1992, the Miami Herald used GIS to report on the aftermath of Hurricane Andrew. GIS helped the Herald show that shoddy construction and lax inspections, not wind speed itself, were to blame for much of the damage. The Herald won the Pulitzer Prize for Public Service the next year for its hurricane aftermath stories and inspired journalists to use GIS more widely.

Since then, journalists have used GIS to report on nearly every topic: local crime, property values, campaign contributions and many others. In health reporting, journalists have used the programs to show how areas with an abundance of bars also have high rates of drunken-driven driving accidents and to identify inner-city neighborhoods with alarming rates of lead poisoning of children.

But compared with other beats, GIS has been used little in health reporting. So there are plenty of opportunities for enterprising journalists.

How do you start?

• First, you should be comfortable working with health data points that are structured in columns and rows, because that's what GIS programs use. If you've used Microsoft Excel spreadsheets or the Access database manager, you're off to a good start.

• Second, you'll need the GIS software and an Intel-based computer. Many journalists use ESRI ArcView. Others use MapInfo Professional or Maptitude. Maptitude is the least expensive commercial GIS. Journalists can also use the My Maps feature of Google Maps to create basic point maps that display locations over streets or satellite images. There are some free open source programs, but they can be difficult to use, poorly documented and not at all robust.

• Third, you'll need geographic data to display maps. Most GIS software vendors provide some geographic files with the program installation discs. Chances are, you'll get things like census tracts, major roads, county boundaries and city points. You'll want to meet your local and county government GIS folks, because they can lead you to more data. Some public health departments in larger cities also have their own GIS experts, who map such things as reported lead exposures or food illness outbreaks.

• Fourth, you'll need some attribute data. This is the data stored in tables that journalists already use. This can include West Nile Virus infection rates by county, blood lead levels for children by census tract, or fetal and infant mortality rates by county. In addition, you can tap into a wealth of data about HIV/AIDS, cancer, births and sexually transmitted diseases and show county- or metro-area patterns.

You'll also want to download geographic data from your state GIS clearinghouse and federal agencies. Some of these web sites offer health geography, such as hospital locations and rural public health clinic sites.

Keep in mind that health agencies are prohibited from releasing data if it would invade an individual's medical privacy. You may need to negotiate with the health agency to get summarized data, or data that lacks identifying details. In addition, you should be familiar with how your state laws treat GIS data. The Reporters Committee for Freedom of the Press has a useful online guide.

Ask for help

You might need some outside help to evaluate the data that are available. For example, cancer cluster analysis is outside the reach of the base GIS programs and most journalists. To pursue such a story, you would need more sophisticated software and expert assistance.

And be aware that mapping programs are more difficult to use than spreadsheets or database managers. Many journalists have gotten up to speed by taking specialized training. I am the lead instructor for three-day GIS "boot camp" seminars offered in Columbia, Mo. by Investigative Reporters and Editors and the National Institute for Computer-Assisted Reporting, for which I also serve as academic adviser. In addition, many universities and community colleges offer GIS training sessions that can be worthwhile.

And don't forget to ask your newsroom's art department or graphic artists if they can help you. You may find that there is already an expert on the software right in your building. Include these colleagues early in the planning process so they can help you to decide how to best illustrate your reporting.

After you start using GIS, you'll find the number of stories you can make better are limited only by your curiosity and time.

David Herzog is associate professor of newspaper journalism at the University of Missouri School of Journalism and the academic adviser to the National Institute for Computer-Assisted Reporting (NICAR).