Marketing planners often use geographical information systems (GISs) to help identify suitable retail locations, regionally distribute advertising campaigns, and target direct marketing activities. Geographical information systems thematic maps facilitate the visual assessment of map regions. A broad set of alternative symbolizations, such as circles, bars, or shading, can be used to visually represent quantitative geospatial data on such maps. However, there is little knowledge on which kind of symbolization is the most adequate in which problem situation. In a large-scale experimental study, the authors show that the type of symbolization strongly influences decision performance. The findings indicate that graduated circles are appropriate symbolizations for geographical information systems thematic maps, and their successful utilization seems to be virtually independent of personal characteristics, such as spatial ability and map experience. This makes circle symbolizations particularly suitable for effective decision making and cross-functional communication.
Keywords: data visualization, spatial marketing decisions, symbolization, geographical information systems thematic maps, cartograms