symbols. The whole “map” should balance cartographic representation
needs with the underlying geographic representation.
8. When is an equal interval classification useful?
The equal interval classification is suited for ordinal, interval, or ratio
ranges of attribute values that are evenly distributed.
9. How is a histogram useful?
A histogram is useful for graphically showing the range of attribute values.
10. Why is the Jenk's classification widely used?
Based on statistical techniques to identify clusters in data, the Jenk's classifi-
cation minimizes variance within clusters. The homogeneous classes usually
offer a better cartographic representation with wide-ranging attribute val-
Cromley, E. K., & S. L. McLafferty. (2002). GIS and Public Health . New York: Guilford.
Kraak, M. J., & F. J. Ormeling. (1996). Cartography: Visualization of Spatial Data .
Harlow, Essex, UK: Longman.
MacEachren, A. M. (1994). Some Truth with Maps: A Primer on Symbolization and
Design . Washington, DC: American Association of Geographers.
MacEachren, A. M. (1995). How Maps Work: Representation, Visualization, Design . New
York: Guilford Press.
McMaster, R., & K. S. Shea. (1992). Generalization in Digital Cartography . Washington,
DC: American Association of Geographers.
Monmonier, M. (1991). How to Lie with Maps . Chicago: University of Chicago Press.
Robinson, A. H. (1984). Elements of Cartography . New York: Wiley.
ColorBrewer offers an excellent resource on uses of color in cartography online at
For practical guidelines for U.S. NPS Mapmaking (Chapter Mapmaking for Park-
lands), see www.nps.gov/nero/interpanded/graphics/idt2p3.pdf
The practical guidelines developed by the US Forest Service are available online at