Community and Regional Planning Program


Date of this Version



Cantarero, R., de Guzman, M. R. T., Taylor, S., Choi, J-K. & Hong, S-H. (2018). (Mis)Communicating with Geographic Information System Mapping: Part 1--Choosing Units of Representation. Journal of Extension, 57 (2).


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Extension professionals are increasingly using geographic information system (GIS) technology to develop and inform programs and services. In this article, we use a mapping exercise to demonstrate how the unit of data can be applied and inadvertently misrepresented in GIS mapping. We contrast the use of counts, percentages, and location quotients with the same data and the resulting divergence in maps. The discussion addresses ideal circumstances for using each unit of data. Overall, the article illustrates the need for Extension professionals to be cognizant of the benefits and limitations of various units of data to avoid miscommunication when using GIS mapping.