Visualize This: The FlowingData Guide to Design, Visualization, and Statistics

What to Look For

You read maps much the same way that you read statistical graphics. When you look at specific locations on a map, you still look for clustering in specific regions or for example, compare one region to the rest of a country. The difference is that instead of x- and y-coordinates, you deal with latitude and longitude. The coordinates on a map actually relate to each other in the same way that one city relates to another. Point A and Point B are a specific number of miles away, and it takes an estimated time to get there. In contrast, the distance on a dot plot is abstract and (usually) has no units.

This difference brings with it a lot of subtleties to maps and cartography. There’s a reason The New York Times has a group of people in its graphics department who exclusively design maps. You need to make sure all your locations are placed correctly, colors make sense, labels don’t obscure locations, and that the right projection is used.

This chapter covers only a handful of the basics. These can actually take you pretty far in terms of finding stories in your data, but keep in mind there’s a whole other level of awesome that you can strive for.

Things can get especially interesting when you introduce time. One map represents a slice in time, but you can represent multiple slices in time with several maps. You can also animate changes to, say, watch growth (or decline) of a business across a geographic region. Bursts in specific areas become obvious, and if the map ...