The Census Bureau released the 2009 ACS (1 year) data in late September.
http://factfinder.census.gov/servlet/DatasetMainPageServlet?_program=ACS
&_submenuId=&_lang=en&_ts=
This is the first time that sub-county (Place) totals were added to the
weighting procedure. Therefore, you may see some large differences
between 2008 and 2009 ACS 1-year results, based on this new method.
(The previous weighting method was restricted to county level data.)
I attended the Washington State Data Center meeting on Nov 5, and the CB
reported that there were large differences in Detroit and Omaha, for
example.
We have previously reported that the lack of sub-county estimates was
problematic for some cities. Please see our CTPP profile sheets using
2005-2007 ACS
http://ctpp.transportation.org/Pages/profiles.aspx
where we recommended that you might want to use independent city totals
as controls. So, we hope that that use of sub-county controls will help
the ACS in the long run, but in the short run, it is probably not a good
idea to make a year-to-year comparisons with 2008 and 2009 ACS 1-year
results.
In general, my recommendation is to use 3-year ACS tabulations when
possible, because of the increased number of unweighted survey
responses.
Other news: The CTPP (using 2006-2008 ACS) will be going into software
beta-test this week. This round of CTPP, with more than 200 tables,
will use a web-based data access system. The tabulations are
restricted to geographic units with more than 20,000 residential
population.
Selected home-to-work flow tables (county-to-county and place-to-place)
are available on the Cambridge Systematics ftp site:
ftp://ftp.camsys.com/temp/outgoing/CTPP/New%20CTPP%20ACS/
<ftp://ftp.camsys.com/temp/outgoing/CTPP/New%20CTPP%20ACS/>
Elaine Murakami
FHWA Office of Planning
206-220-4460