The Johns Hopkins Gazette: August 16, 1999
August 16, 1999
VOL. 28, NO. 42


Software Turns Data Into Graphic Maps

By Greg Rienzi
The Gazette
Johns Hopkins Gazette Online Edition

Mapmaker, mapmaker, make me a map. James Gillispie, head of the Government Publications/Maps/Law Library at the Milton S. Eisenhower Library at Homewood, wishes more people came into the library singing this version of the popular Broadway tune.

For a university literally awash in data, the ability to put numbers and statistics into a manageable and attractive form, such as a color-coded map, is something Gillispie is certain more people need to take advantage of.

But why is Gillispie so concerned about maps?

In addition to his other duties, Gillispie is also Hopkins' own mapmaking guru of sorts. The tool of his trade is the ArcView geographic information system, a desktop program that enables users to analyze data and create custom-designed maps.

MSEL has been authorized to offer an ArcView site license program that allows Hopkins faculty, staff and students to load ArcView onto any university-owned computer for use in teaching, research, course work or if they're just curious how something would look on a map.

The program started last year, and Gillispie says the software is currently loaded onto 125 Hopkins machines. He would like to see that number increase.

"I'm hoping it will be used by more people, and we will have it on as many workstations as possible," he says. "Everyone has a need for showing statistical data in a spatial or graphic format. Maps can help you manage your data. It isn't just another table."

Hopkins owns copies of the latest version of the popular mapmaking software. Gillispie says the earlier versions were less intuitive, and users often needed an experienced technician to guide them through some of the necessary steps. With the new version it is easier to import data, and users now can incorporate satellite imagery into their maps.

Yet the most noticeable improvement, according to Gillispie, is the site-license program that allows the software to leave the library.

"Five years ago, people couldn't do this on their desktops," Gillispie adds. "Now they can work on their maps day and night and at their own pace."

The software works by reading codes of information in a spreadsheet format, like that created by Excel. The codes are then transplanted into what is called a boundary or shape file, such as the state of Maryland and its county borders.

If a user wanted to make a map illustrating the outbreak of a disease by county, for example, the software could be told to designate a color shading based upon the number of reported cases in each county. Typically, for visual effect, a darker shade is given to the higher number.

Gillispie says maps also can be used for internal Hopkins questions such as, Where are most alumni residing?

"A map helps folks see patterns and associations," Gillispie says. "It helps the user interact with statistical information and makes the data come alive."

The Eisenhower Library currently has boundary files, which are based upon latitude and longitude, for states, counties, ZIP codes, census tracks and block groups. Boundary files for smaller areas, such as a city neighborhood, sometimes can be obtained from private or public organizations that keep demographic data. The library also has an extensive catalog of demographic data on CD-ROM, including recent U.S. census data, that comes in an ArcView-compatible data base format.

Users can supply their own data, which must be in spreadsheet form, Gillispie says.

"Sometimes people think all the data are here and ready for them. For instance, someone might want information on left-handers, but the government doesn't have that type of information," Gillispie says. "You can find data of all types from organizations or governments via the Internet. The question is, though, Will the data be in a useful form?"

ArcView comes with a tutorial feature that teaches the fundamental aspects of mapmaking. Training sessions also are given by library staff. It takes about two hours to learn the basics of the software, yet to really appreciate all the program's features, Gillispie recommends a two-day class, which is available by appointment.

Currently, Hopkins' most frequent users of ArcView, according to Gillispie, are researchers at the School of Public Health.

Stan Becker, associate professor in Population and Family Health Sciences, recently completed a 50-map booklet using ArcView, a project that took nearly three years. The maps were used to illustrate the research findings of scientists who were looking for ways to decrease infant mortality, fertility rates and the transmission of HIV in West African countries.

Becker, who was involved in operation research, says he used demographic and health surveys that were conducted in the past decade as his data sources. Among the variables his team was looking to isolate were the percentage of mothers who received prenatal care and the percentage of children who received no vaccines at all. By using a rainbow design, lighter to darker shades, the data just leaped off the page.

"Right away you could see that for a lot of the variables the coast is much better off than the hinterland," Becker says. "Everybody sort of knows that things are better off on the coast, but this was just very dramatic. I think it's one of the first times it has been documented in this way."

Gillispie says he enjoys seeing the reaction people have when they print out their maps and their suspicions are confirmed.

But a map really becomes useful, he says, when it tells you something you weren't expecting to find.