Teaching Spatial Concepts with Zonal Statistics

Blog Post created by jkerski-esristaff Employee on Jun 27, 2013
I recently created a set of activities based on using web-based GIS tools to teaching spatial thinking using drive-time buffers, and another set of activities that use viewsheds.   Another type of spatial analysis computes and summarizes data from points, lines, or polygons, and is called “zonal statistics.”  To easily use an application of zonal statistics, use this map to summarize population in specific areas.

Calculating the population of the Atlanta area with zonal statistics tool.

After accessing the map, click "Summarize Population" in the  lower left section of the map and then draw a polygon that encompasses Atlanta, Georgia.

What is the population of the Atlanta area?  Why is your result likely to be different each time you draw the polygon?  How does the population of an area of similar size in rural Georgia compare to the population of Atlanta?  How does the population of an area of similar size in rural Wyoming compare to rural Georgia?  Compare your counts to areas of similar sizes in the Ganges River basin in India, or to an area in the Sahara Desert.  Why is the base data that is being used for the population counts critical to the specific results you receive from these calculations?  Test the results over the ocean:  Do the counts total zero?

How might you be able to use this tool in teaching and learning about issues of map projections, data quality, zonal statistics, and other spatial concepts?