[CTPP] 2009 ACS 1-year data

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