Generally speaking, the ACS estimates use the FSCPE's (Federal-State Cooperation for Populatin EStimates) state and county estimates as controls but not the exact figures. It is more complicate with detailed adjustments without documented explanations. At least it happens to the 2004 ACS estimates to Colorado counties and municipalities. - Richard Lin, Ph.D. Demographer Colorado Division of Local Government (303)866-4989, fax (303)866-2660 richard.lin(a)state.co.us Jeffrey: [I'm cross-posting my message to the national census-transportation listserv] You raise important points: 1. How does the Census Bureau weight & expand the American Community Survey? Do they weight it to match sub-county "control totals"? 2. How will formula allocation programs (HUD, HHS, DOT) utilize American Community Survey in allocating funds to local jurisdictions? How will formula allocation programs handle the higher standard errors, and confidence intervals, associated with the ACS? Answers: 1. The Census Bureau, to the best of my knowledge, uses counties as the finest geographic level for expanding and weighting ACS data. They do not use sub-county or place-level control totals (e.g., like they did with the weighting of decennial long form data to match decennial short form control totals). The "control totals" the Census Bureau uses are the state-federal cooperative population estimates program, which produces data on TOTAL population by age by sex by race/hispanic status. (How the Bureau adjusts these county-level population estimates to remove the group quarters population, I don't know.) Again, this is all to the best of my knowledge. For example, our State Department of Finance reports the population for Alameda County, in 2004, as 1,497,000. If we assume the same 1.9% of Alameda County's population of group quarters, then this means about 1,469,000 persons-in-households in Alameda County in 2004. The ACS measures 1,427,827 household persons in Alameda County, a difference of 4.7%. Why this difference? The pop estimates that the Bureau is using are perhaps different (?) than the pop estimates that the California DOF released this past May. To state that the weighting and expansion of American Community Survey data is an "issue" is a gross understatement. It's a really, really big issue. 2. In terms of the question "how will allocation formulas be affected by ACS?" This is really a very, very significant issue and honestly, I don't know. For example, the president recently signed the federal transportation reauthorization bill (SAFETEA-LU). There are two formula programs based on the distribution of DISABLED persons (for the "New Freedom Program") and the number of PERSONS BELOW THE 150% POVERTY LEVEL (for the Jobs Access-for-Reverse Commuting - - JARC Program), based on urbanized area population. Right now, the only urbanized area data on disabled population and poverty population is from the decennial census. So, to allocate data NOW, the USDOT would need to rely on Census 2000 data. When data is available from the 2005-2007 ACS (3-year accumulation of data), down to the SMALL URBANIZED AREAS (50,000 to 65,000 population), the USDOT MAY CHOOSE TO USE THE ACS 3-YEAR DATA TO ALLOCATE JARC & New Freedom funds....Hopefully the 3-year ACS data is less jumpy & jittery than the one-year data we've seen over the past four years. (An additional point to make is that the disability data from the decennial census isn't that good. The disability data from the ACS should be a much better indicator of disability levels.) The other example, probably more near and dear to city planner's hearts, is the allocation of community development block grant (CDBG) funds based on census-tract level estimates of poverty (?) population. I think the funding agency will have to at least look at using the five-year accumulation of ACS data, but I'm concerned (as are many others) about the "bright line" rules that regulate whether an area does or doesn't receive CDBG funds. [I am out of my element & comfort zone when talking about CDBG fund allocations. If there's a HUD-Census user forum that discusses these issues, that would be great information to share. Here is a link to a 2002 vintage HUD report on the ACS. I haven't read it yet: http://www.huduser.org/publications/polleg/acs.html I've heard comments from the Census Bureau folks that the ACS data is best for "characteristics, not counts" but the Bureau will need to realize that we data users want it all: both characteristics (shares, rates & proportions) and counts (# of persons below poverty level, # of disabled, # of zero-vehicle households, # of transit commuters, etc.) My strongest recommendation is to "cross-validate" the ACS data with other, local administrative data. The best cross-validation, at a city level, will be to compare the citywide total housing unit estimate from the ACS against the City's own records on total units.... This is a long-winded "I don't know" response. Chuck ************************************************************** Charles L. Purvis, AICP Principal Transportation Planner/Analyst Metropolitan Transportation Commission 101 Eighth Street Oakland, CA 94607-4700 (510) 817-5755 (office) [new, 8/1/05] (510) 817-7848 (fax) [new, 8/1/05] www: http://www.mtc.ca.gov/ Census WWW: http://www.bayareacensus.ca.gov/ ************************************************************** This new ACS data raises a lot of questions for us. It shows our 2004 population as 365,266 with lower/upper bounds of 338,601 and 391,931 Our 2000 population was over 399,000. Even subtracting out the 7,000 or so households in group quarters (who aren't counted in the ACS), this would give us 392,000 in 2000, but only 365,266 in 2004, despite a significant increase in our housing stock and by all indications an increase in population. Department of Finance estimate is 411,319 for 2004 and 412,318. Does anyone else have similar problems? This kind of undercounting can cost cities a LOT of money. _________________________________ Jeffrey P. Levin (jplevin(a)oaklandnet.com) Housing Policy & Programs Coordinator City of Oakland/Community & Economic Development Agency 250 Frank Ogawa Plaza, 5th Floor Oakland, CA 94612 510/238-3501 FAX: 510/238-3691 http://www.oaklandnet.com/government/hcd _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news