22.312 ExploreMa Stephen Egbert and Terry Slocum (1992) developed ExploreMap to assist users in exploring data commonly mapped with choropleth symbolization. In developing ExploreMap, their intention was not to create the ulti mate data exploration tool, but rather to provide a pro totype that others might improve on. In contrast to Moellering's video distribution, ExploreMap and other software described in this chapter distributed via diskette, CD-ROM, or over the Web. ExploreMap operates in two basic modes: Design and Explore. Design is necessary for creating maps, whereas Explore includes methods for exploring data, and thus is the focus of this chapter. Two of ExploreMap's functions, Areas and Overview, correspond to the two types of information that can be acquired from a map: specific and general (see section 1.2) To illustrate how Areas provides specific information, consider two of its options: Single Area and Ratio of Areas. The Single Area option is used to determine the exact value of an enumeration unit either by pointing at it with the mouse or by typing its name. contrast, on a traditional paper map, the value for an enumeration unit is determined by visually com paring a shade on the map with shades in the legend-for example, on a classed map. the best estimate is a range oi values shown in the legend Most current data explo- ration software includes an option similar to the Single Area option. The Ratio of Areas option is used to deter mine the ratio of values for two enumeration units: When Data values on a paper map can be displayed within enume ation units, but this detracts from the visualizaticn of the map pattern moreover, values cannot be placed within small units.