ACS Geo-Restricted

[frederickgifford]

Can anyone point me to documentation that describes reasoning behind the fields that are Geo-Restricted in the ACS data. Specifically interested in Place of Birth and Citizenship.

[HelenThompson]

Hi Frederick

All Census Track only data is georestricted currently in BA Web. This includes ancestry, country of origin and other topics inducing detailed population and occupational data. There are about 800 variables for which the restrictions are in place when using them in analysis and apportionment based workflows.

We will provide support for Tract level data in an upcoming release as we have refined support for new statistical models which take into account margin of error and reliability scores. Currently reapportioning these datasets to smaller geographies or informal trade areas does not fully encompass error models.

For example, British Ancestry in a tract in Redlands is +/- 24 people (see below) with a COV of 112% for an estimated population of 13 people. So the range is 0 or 37 people.  The COVs vary considerably and often there is zero people with the characteristic but margins of errors in double figures.

I hope this helps

Best
Helen

[frederickgifford]

Hi. Thanks for the reply but I guess I don't understand. Citizenship and nativity are available in the ACS 5 year data at the block group level but they are not in the BA ACS data and I was trying to understand why.

Thanks.

Fred

[HelenThompson]

Most ACS data has acceptable margins of error at the tract level across a wide ranges of topics. At the block group level, the more straightforward attributes like Total Population may have acceptable margins of error at the block group level, but anything which then further segments attributes like population by race and age have suppressed values (0) or high margins of error. There are already these issues at the Tract level so they become much greater and more challenging for interpretation, aggregation, and analysis at the block group level. Although data is available it does not suit all GIS use cases.

If you would like to add your own ACS data at the block group level, you can use the add custom data workflow.

Best wishes

Helen