RE: [SPAM] - Re: [CTPP] ACS 2005-2007 Population Estimates - Email has different SMTP TO: and MIME TO: fields in the email addresses

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(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Patty Becker Sent: Friday, June 26, 2009 9:41 AM To: ctpp-news(a)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) --------------------------------------------------------------- _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news ------------------------------------------------------------------------ ------------------------- Patricia C. (Patty) Becker 248/354-6520 APB Associates/SEMCC FAX 248/354-6645 28300 Franklin Road Home 248/355-2428 Southfield, MI 48034 pbecker(a)umich.edu