The reasoning behind TADs at 20,000 is so there will be a full layer coverage of three year ACS data. The ACS is released at specific geographies depending on how many years are being released. For 3 - year ACS data, the population threshold for smallest geography is 20,000. If you delineate your TADs smaller than 20,000, data will not be reported for them in three year data sets and we will have the "swiss cheese" coverage we currently have.
-----Original Message-----
From: ctpp-news-bounces@chrispy.net on behalf of John M. Sharp - ACOG
Sent: Tue 6/28/2011 1:37 PM
To: ctpp-news@chrispy.net
Subject: [CTPP] RE: TAZ delineation update
Being a little slow on the TAZs.
However, a question on the TADs. What do we lose (data wise) if we have some TADs that total only 15,000, rather than the 20,000?
Thanks,
John
From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Elaine.Murakami@dot.gov
Sent: Thursday, June 16, 2011 2:49 PM
To: ctpp-news@chrispy.net
Subject: [CTPP] TAZ delineation update
Over 100 agencies have ALREADY submitted their files to the Census Bureau Geography Division, with at least 10 agencies submitting files today (June 16).
The CB GEO staff have found that the TAZ files look pretty good, and although there are some TAZs that look "too small" these are often in areas with parks or water areas. They also said that the TADs look VERY good, with very good adherence to the 20,000 population threshold.
Thank you to everyone! I know the rest of you who are participating in the program are working very hard to complete this task. Getting the TAZ and TAD into Census TIGER is one step for the CTPP 5-year tabulation. This tabulation will use ACS records from 2006-2010. AASHTO is expected to submit the 5-year table list to the Census Bureau's Disclosure Review Board this July.
Re: TAZ, don't call me :), please call the Census Bureau Geography Division at 301-763-1099. Email: geo.taz.list@census.gov<mailto:geo.taz.list@census.gov>
Elaine Murakami
FHWA Office of Planning
206-220-4460