Mapping your way to great demographic stories

Investigative Reporters and Editors, Inc. The IRE Journal, Jan/Feb 2004 by Herzog, David

Census data analysis can aid investigative reporting by providing context and adding hard numbers to your hunches. But making sense out of screens full of data arrayed in columns and rows can sometimes prove challenging.

Many journalists have uncovered great information lurking inside census numbers by mapping the data using computer programs called geographic information systems (GIS). They've detected patterns that otherwise might have gone unnoticed just by scanning data tables. And, by adding other map layers on top of their census maps, they've come up with some great stories. Here are some from the past few years:

Shuttle. Soon after the space shuttle Columbia broke apart over Texas in February 2002, Florida Today reporter John Kelly wanted to investigate the risk of shuttle re-entry dangers over populated areas. No one had died on the ground.

Kelly mapped the population density, using data from Census 2000, in the region and then layered maps of Columbia's flight path and the oval "debris footprint" that approximated the area where recovery workers on the ground had found shuttle pieces. Then he added a second oval footprint that showed where the debris field would have been if the shuttle had started breaking up just one minute earlier.

Kelly could see that under the earlier breakup scenario, debris would have hit the Dallas suburbs, where there were three times as many people and houses. (For more details see the July-August 2003 edition of Uplink.)

Voting. Dan Keating, a database editor at The Washington Post, used GIS, voting results and census data to examine claims that punch-card ballots cast by African-American voters in the 2000 presidential contest had been rejected at higher rates than whites because of voting error.

For one of the two articles he did with John Mintz, Keating used 1990 Census data - the latest available - to compare rejected ballots with race in Chicago and suburban Cook County.

By layering a map of the minority voter precincts that he created using the census data over the ballot rejection rates by precinct, Keating saw a clear relationship. The results mirrored those Keating had generated for a similar story about ballot rejection patterns in Florida.

Juries. Mark Houser of the Pittsburgh Tribune-Review wanted to see how well juries in Allegheny County courts reflected the racial make-up of the community. Specifically, he wanted to chec whether the county's jury-picking process systematically overlooked blacks.

The county courts provided a list of the people who had been called to serve on juries for an 18-month period, their addresses and dates served. After Houser removed duplicate names from the list in Microsoft Excel, he moved the data into his GIS program and created a pin map from the addresses.

He also used the GIS program to attach census demographic data to each point so he could tell, for each person's neighborhood, the percentage of the population that was black.

After some more analysis, Houser found that residents of black neighborhoods were half as likely as residents of white neighborhoods to get the call for jury duty. (For more on this story, see the January-February 2003 edition of The IRE Journal.)

Seeing the potential

Journalists have been using GIS as an investigative reporting tool for about a decade. A handful of journalists started using GIS in the early 1990s to look at patterns in data from the 1990 Census. Steve Doig, then at The Miami Herald, saw the potential for GIS as an investigative reporting tool after Hurricane Andrew struck southern Dade County.

The hurricane left an uneven path of damage, and Doig was part of a team at the Herald assigned to investigate the devastation. Doig mapped the damage patterns and overlaid a wind speed map. His analysis showed that the newer homes suffered the greatest damage. Some newer subdivisions with lesser winds had greater damage than older subdivisions with higher winds.

That key fact in hand, the Herald reporters dug into the story and found that poor residential construction and loose regulation contributed to the damage patterns. The stories were part of a package that won the 1993 Pulitzer Prize for public service and spotlighted how GIS could bolster investigative reporting.

Getting started using GIS

Using GIS to uncover information is nothing new, of course. People in a multitude of other professions had been doing it for years before journalists.

Several forces helped to propel GIS into newsrooms during the early 1990s. First was the spread of computer-assisted reporting and the realization that great stories lurked inside databases. Second was the makers of the old command-line GIS programs developed point-and-click versions that were much easier to use.

Meanwhile, government agencies began adopting GIS and creating map data journalists could obtain under public records laws. Around the same time, agencies began posting their GIS data on the Web for free.

So what do you need to get started with GIS?

You will need a GIS program. The three programs most widely used by journalists are Calipee Corp.'s Maptitude ($495 list), ESRI's ArcView ($1,500) and Maplnfo's MapInfo Professional ($1,495).