This page details a specific electronic resource that has been indicated by Villanova Librarians as useful in conducting research.
GIS - Cultivating Spatial Intelligence (GIS Manual-Harvard)
Discusses some principles for portraying quantitative statistics on maps. "There are two fundamental types of quantitative measurements that may need to be mappped: Raw Quantities (such as counts), Measures of Intensity (such as population density or the percentage of the population who are Canadian.)"
Geography and the Environment