Beyond Graduated Circles: Varied Point Symbols for Representing Quantitative Data on Maps

Graduated point symbols are viewed as an appropriate choice for many thematic maps of data associated with point locations. Areal quantitative data, reported by such enumeration units as countries, are frequently presented with choropleth maps but are also well suited to point symbol representations. Our objective is to provide an ordered set of examples of the many point-symbol forms used on maps by showing symbols with linear, areal, and volumetric scaling on repeated small maps of the same data set. Bivariate point symbols are also demonstrated with emphasis on the distinction between symbols appropriate for comparison (separate symbols) and those appropriate for proportional relationships (segmented symbols). In this paper, the variety of point symbol use is described, organized, and encourage, as is research on these varied symbols and their multivariate forms.