GIS 5007: Computer Cartography- Module 4 - Data Classification

This week, we learned about the different types of data classification: quantile, standard deviation, natural breaks, and equal interval.  The quantile method creates even numbers of features in each class. To calculate quantile classes, the number of classes must first be defined. The number of class breaks is calculated by dividing the number of observations by the number of classes.  Standard Deviation is calculated by determining how much the data differs from the mean/average. The natural breaks method is more subjective than the other methods. Generally, the categories are created at the discretion of the GIS analyst. With ArcGIS Pro, the software attempts to generate natural breaks in the data and create relevant categories. Finally, with equal interval classification, each class maintains and equal interval along the number line.  Data including temperatures is a good example of when equal interval classification should be utilized. 

During the lab, we tested all four methods to create maps representing the 65+ population in Miami-Dade County, using U.S. Census Bureau data.  We created a second set of maps, using all four data classification methods, using 65+ older information and normalized data (square miles).