Custom Defined Polygon Areas and Reports

Question

I want to understand how the tool manages the following scenario when using custom defined areas/polygons while generating reports, such as ACS population reports. Let say I have a custom polygon of certain areas and I want to generate a population-based report. Would the population values in this report be adjusted based on the population intersecting the custom polygon or are they based of the entire Census statistical area, that is, blocks, block groups, tracts, etc. intersecting the polygon?

For instance, taking the whole population of a tract when a small portion is within a ¼ buffer can inflate the actual population served. How does the tool manage this scenario?

DonnaBuhr1 · Answer

Hello Ernesto,

My apologies for the delayed response.  ArcGIS Community Analyst employs a GeoEnrichment service that uses the concept of a study area to define the location of the point or area that you want to enrich with additional information. This Data Allocation method allocates block group data to custom areas by examining where the population is located within the block group and determines how much of the population of a block group overlaps a custom area. This method is used in the United States and in Canada. The population data reported for census blocks, a more granular level of geography than block groups, is used to determine where the population is distributed within a block group. If the geographic center of a block falls within the custom area, the entire population for the block is used to weight the block group data.

Please note: Depending on the data, households, housing units, or businesses at the block group level are used as weights. Employing block centroids is best because it accounts for the possibility that the population may not be evenly distributed geographically throughout a block group.

Here is a url to the reference documentation for the data apportionment method used.  https://developers.arcgis.com/rest/geoenrichment/api-reference/data-apportionment.htm

Thank you for using ArcGIS Community Analyst!

Best regards,

Donna