Another thing to keep in mind is that the 3-year and 1-year
estimates are controlled to different years. The 2005-2007 estimates are
controlled (at the county level) to the total population estimate for 2006 while
the 1-year estimates are (obviously) controlled to the 2007 county-level
total population estimates.
Frank Lenk
Director of Research Services
Mid-America Regional Council
From: ctpp-news-bounces@chrispy.net
[mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Patty Becker
Sent: Friday, June 26, 2009 9:41 AM
To: ctpp-news@chrispy.net
Subject: [SPAM] - Re: [CTPP] ACS 2005-2007 Population Estimates - Email
has different SMTP TO: and MIME TO: fields in the email addresses
The first thing to understand is that while the ACS county
estimates are controlled to the census population estimates, the sub-county
estimates are not. The numbers that appear for cities are just what
the weighted data show. For Detroit, they are always too low. There is
always a lag in terms of getting new housing units into the sampling frame (the
Master Address File, or MAF), while there is loss when a sample address turns
out to be demolished or vacant.
I don't know if that the 2010 ACS data are going to be weighted to the census
results. I don't think they've thought about that yet. If they are, there
won't be any problem updating from April to July. We do not usually see redone
intercensal estimates after the census, and I'm sure that there won't be any
adjustment of ACS results.
Bottom line: be very careful in using whole numbers from the ACS, and when you
do, always round them to '00s (hundreds) so that people will understand that
they are estimates and not counts. ACS is really best for the data that are
expressed in percentage terms.
Patty Becker
At 05:28 PM 6/25/2009, you wrote:
For ACS 2005-2007 population and housing occupancy/vacancy
estimates, are people finding discrepancies between ACS and other data sources,
particularly in sub-county geographies? ACS estimates are controlled at
the county level and, like the ACS 1-year data, ACS 2005-2007 population
estimates are showing disagreement with other data sources. For example,
the Oakland 3-year ACS estimate shows the population at 372,000, when CA Dept.
of Finance estimates are over 400,000. This runs counter to the
on-the-ground anecdotal experience - ACS shows a loss of 30,000 people during a
period that showed an increase of 10,000 housing units.
Will the decennial census correct this? My understanding is that
Census 2010 numbers will be used to control 2010 ACS characteristic data.
There will need to be some adjustment, however, given that the decennial census
benchmarks population at April 1, and ACS uses a July 1 population
number. It's also my understanding that population estimates for
2001-2009 will be updated, though retroactive adjustments for ACS
characteristics will not be done. Does anyone else know something
different about this?
Other thoughts about this?
Thanks,
Shimon
---------------------------------------------------------------
Shimon Israel
Associate Transportation Planner/Analyst
Metropolitan Transportation Commission
101 Eighth Street
Oakland, CA 94607-4700
(510) 817-5839 (office)
(510) 817-5848 (fax)
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Patricia C. (Patty) Becker
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