UNO Campus
 

How the Centers were Created

Centers for this project were created in a mapping program called ArcMap, created by Environmental Systems Research Institute (ESRI). According to ESRI, "The mean center is a point constructed from the average x and y values for the input feature centroids." The figure below shows this process with many points averaged to obtain the location of one central point.

 



 
 
Omaha, Nebraska Census Blocks used for the mean center calculations

The dialog box for a mean center calculation in ArcMap is below. Notice the calculation requires a feature class (spatial data, for example, block groups) containing centriod values as well as an output destination for the new feature class (a center calculation) being created. The field labeled "Weight Field" is optional and is useful for calculations that rely on a variable to "push or pull" the mean center location towards or away from "lighter or heavier" centroids. Centroids for this project were at the census block level (the smallest division of 2000 Census data).

 

   
 

 

 

   

Click on the map for a larger size

Click here for a PDF version of the map