PrintComparing vs. Combining
As demonstrated by previous examples, multivariate maps are often challenging—both for cartographers to create and for readers to interpret. However, if you need to map multiple variables simultaneously, but want to avoid a complex multivariate map (for example, when creating a map for a presentation slide) there is another option: simply creating multiple, adjacent maps. This is called small multiple mapping.
Small multiple maps are particularly useful for depicting data over time, as they can be arranged in a linear sequence, the way that time is typically depicted. With the increasing popularity of web maps, small multiple maps can be more easily replaced with a animated maps, where each map appears as an individual frame. Despite the advantages of animated maps (e.g., creating visual interest, efficient use of layout space), there are still benefits to traditional small multiple mapping. One primary advantage is the ability to simultaneously compare the various maps.
We can imagine combing the set of maps in Figure 7.6.1 with some sort of transparent layering, or perhaps turning it into an animated map. However, a single map with multiple transparent layers would be visually complex, and viewers of an animation would have to wait for the animation to loop—or scrub through the frames—in order to compare two specific maps. Here, simple works well. If your presentation is still too complex, you may consider reducing the amount of information being presented. Figure 7.6.2 is an example of small multiple mapping that only uses two multiples.
