Lessons for data visualization from Steven Johnson's "The Ghost Map"

Blog post at PeteSearch

Snow wasn't the first person to draw these kinds of maps, he wasn't the first to draw them to track disease, and in fact he wasn't even the first person to map this particular outbreak! The Sewer Commision produced a very detailed map showing the death locations. The power of Snow's version came from his decision to leave out a lot of details (sewer locations, old grave sites, etc) that cluttered up the Commision's version. Their map was so muddled that it didn't tell a story, but Snow's was stripped-down to show exactly what he needed to bolster his theory that the epidemic spread from the water pump.

As Johnson puts it in his book "the map was a triumph of marketing as much as empirical science".