Robert: Well, the ACS data is what it is - can't get around that. The sample size is smaller than that used for the 2000 Decennial Census sample survey (the equivalent of about 12% versus about 16%), so there are indeed many who are dissatisfied with the resulting higher margin of error. This dissatisfaction is probably increased because Census did not report the margin of error until the ACS came along, in the past allowing Census users (myself included) some degree of blissful ignorance of the actual level of uncertainty. At the small area level, notable error rates actually have been in the sample data all along. Whether it will "not be good" at the block group level will depend on how good it has to be for your purposes, and on what data element you are measuring (e.g., smaller percent margin of error for SOV rates than for bicycle commuters). Block groups are of comparable size nationwide, for small communities and large, ranging in the 2000 Census from about 600 to about 3000 and averaging about 1200 (the 2000 Census geography will be that used in the 2005-09 ACS product). The ACS block group data consequently will be of comparable utility for small communities and large, since it is the size of the block group that counts, not the size of the community. One exception to this rule: Census uses higher sampling rates in low population areas (e.g., small towns and small rural counties) so that they can get a large enough sample to achieve statistical significance when they have to report data for small political jurisdictions. Bottom line: for better or worse, ACS 2005-09 block group data is all we will have in the next few months with small area socio-economic and journey-to-work characteristics, unless one has the resources to do one's own surveys. As Ed Christopher pointed out, the 2010 block data also will be available for our use in delineating new TAZs, though it will be limited to basic demographic information, dwelling counts, and owner vs. renter vs. group quarters. Pete Swensson, Senior Planner Thurston Regional Planning Council 2424 Heritage Ct. SW Olympia, WA 98502 (360) 741-2530 (direct line) (360) 956-7575 (main desk) (360) 956-7815 (fax) swenssp(a)trpc.org This e-mail and any attachments are for the use of the addressed individual. If you have received this e-mail in error, please notify our systems manager. TRPC has taken responsible precautions to ensure no viruses are present in this e-mail, however we do not accept responsibility for loss or damage arising from the use of this e-mail or attachments. From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Allen, Robert Sent: Monday, October 11, 2010 7:19 AM To: 'ctpp-news(a)chrispy.net' Subject: RE: [CTPP] RE: TAZ delineation for CTPP (2006-2010) tabulationSCHEDULE Pete, The information that I have been receiving through the Texas Transportation Institute has been that the 2005-2009 ACS data will not be good at the block group level, at least not for places like Abilene, TX (pop. appx. 120,000). If you have been getting different information, I would very much like to know, as it is very important due to the timetable for our current travel demand model update. Robert R. Allen, AICP Abilene MPO Transportation Planning Director 400 Oak Street, Suite 102, Abilene, TX 79602 Office (325) 676-6243 Fax (325) 676-6398 Cell (325) 513-4615 ________________________________ From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Pete Swensson Sent: Friday, October 08, 2010 3:36 PM To: ctpp-news(a)chrispy.net Subject: RE: [CTPP] RE: TAZ delineation for CTPP (2006-2010) tabulation SCHEDULE I'll just jump in. I am on the CTPP Oversight Committee that prepared the "Business Rules" for delineating the TAZs for which Census will report the data. Census has been collecting journey to work data through the American Community Survey nationwide since 2006 that will go into the CTPP 2006-2010 tabulation. They need all of us FIRST to delineate our TAZs for them to create the tabulation. So you won't be able to wait to see the data first in order to determine how best to delineate your TAZs. Sometime around December of this year, the 2005-2009 5-year dataset will come out, providing data down to the block group level (2000 census block group geography), and you may find that useful in determining how you want to delineate your TAZs. It won't be exactly what you are looking for geographically, the standard tables will not be as specifically tailored to transportation modelers, and the data won't be benchmarked to this year's decennial census like the 2006-2010 dataset will. But it may give you some useful data. Pete Swensson, Senior Planner Thurston Regional Planning Council 2424 Heritage Ct. SW Olympia, WA 98502 (360) 741-2530 (direct line) (360) 956-7575 (main desk) (360) 956-7815 (fax) swenssp(a)trpc.org This e-mail and any attachments are for the use of the addressed individual. If you have received this e-mail in error, please notify our systems manager. TRPC has taken responsible precautions to ensure no viruses are present in this e-mail, however we do not accept responsibility for loss or damage arising from the use of this e-mail or attachments. From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Curt Hutchings Sent: Friday, October 08, 2010 12:20 PM To: ctpp-news(a)chrispy.net Subject: [CTPP] RE: TAZ delineation for CTPP (2006-2010) tabulation SCHEDULE Elaine, Please excuse my ignorance. I have had questions about how the Census Dept. would collect TAZ data for the Census. I have been waiting for information like you have provided below. Can you give me any additional information? We are in the process of modifying our TAZ structure now and want, If possible to use the new information in this count. Any thoughts? Thanks, From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Elaine.Murakami(a)dot.gov Sent: Wednesday, October 06, 2010 10:32 AM To: ctpp-news(a)chrispy.net Subject: [CTPP] TAZ delineation for CTPP (2006-2010) tabulation SCHEDULE At our monthly CTPP Technical meeting last week, April Avnayim of the Census Bureau Geography Division, gave us an update on the TAZ delineation software schedule. November 2010: agencies verify contact names by reviewing file at Cambridge Systematics ftp site, and report any changes to Liang Long. December 2010: final delivery of software by Caliper to CB February 2011: web-based training coordinated with FHWA January thru March 2011: delivery of software and Census 2010 data and geographic files on a rolling basis. Each state will get 3 - 4 months to delineate their TAZ and TADs and return the files to the Census Bureau. July 2011: all files MUST be returned to CB Geography Division. Please note: TAZs for CTPP tabulation do not necessarily match the TAZs for your travel demand model. Because the ACS sample is small, some agencies are planning to make the TAZs for CTPP LARGER than their model TAZs, e.g. combining their model TAZs together. Also, TAZs for CTPP are census block equivalencies. You will NOT be able to modify the TIGER segments (which was possible in the CTPP2000). Finally, agencies are NOT required to define TAZs or TADs. If you do not define TAZs, then census tracts will be used as the default geography for CTPP (2006-2010) tabulation. However, even if you do not define TAZs, we recommend that you create TADs (population threshold of 20,000) by combining census tracts together. The TAZ business rules are posted on the FHWA webpage: http://www.fhwa.dot.gov/ctpp/tazddbrules.htm <http://console.mxlogic.com/redir/?a8VV5dd5MSyeKCy-r01eAP6Yxmv4qCsJdpr9W a8848JD_jw26XYDuZXTLuZPtPtFHb5UuoEn8lrxrW0GNecGb5K1FJ54QsLfCQkTD6nCknxNJ NwSqmN84xob6BQQg0Ag0AQg8uva7Xelo6y1SIjh090Ab1oQg6yxeZT2WtQrCyAQgjQwSvIVl wq81wi2UQ71cazhEwdPYfDwedECQjqbwUQszDSjhOrovBc>

Robert: The income data is tricky in another way: in the past Decennial Census sample data, the question was asked of survey respondents around the time of Census day, April 1. They were asked, what was their income for the previous calendar year? Most people would have just done their income taxes, and would have a pretty reliable idea of their income for that period. Now ACS surveys the population every month of the year, asking what was their income for the prior 12 months, which now most often splits calendar years. Comparisons in 2000 of the Decennial Census Sample Survey versus the ACS method have shown that this new method results in a lower estimate of income than the methodology in the old survey, and I suspect it is because people now are mostly guessing at their income rather than having a precise calculation at hand. Thus income is longitudinally comparable using ACS from one year to the next, but it is not longitudinally comparable using ACS versus 2000 Census. You can expect it to be reasonably comparable horizontally from one neighborhood to another for the same time period. On the other hand, the Great Recession may have affected some neighborhoods more than others, and this may not be captured very well by the long time period represented by the ACS 5-year data. Pete Swensson, Senior Planner Thurston Regional Planning Council 2424 Heritage Ct. SW Olympia, WA 98502 (360) 741-2530 (direct line) (360) 956-7575 (main desk) (360) 956-7815 (fax) swenssp(a)trpc.org This e-mail and any attachments are for the use of the addressed individual. If you have received this e-mail in error, please notify our systems manager. TRPC has taken responsible precautions to ensure no viruses are present in this e-mail, however we do not accept responsibility for loss or damage arising from the use of this e-mail or attachments. From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Allen, Robert Sent: Monday, October 11, 2010 11:57 AM To: 'ctpp-news(a)chrispy.net' Subject: RE: [CTPP] RE: TAZ delineation for CTPP (2006-2010) tabulationSCHEDULE Pete, Thanks for your reply. I am looking primarily for household incomes as the most urgent data. Income data has always been a notoriously subjective item with wildly varying degrees of reporting accuracy, both intentional and unintentional. I obviously need to do more direct research with the Bureau about the ACS usefulness at various population thresholds. Robert Robert R. Allen, AICP Abilene MPO Transportation Planning Director 400 Oak Street, Suite 102, Abilene, TX 79602 Office (325) 676-6243 Fax (325) 676-6398 Cell (325) 513-4615 ________________________________ From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Pete Swensson Sent: Monday, October 11, 2010 1:19 PM To: ctpp-news(a)chrispy.net Subject: RE: [CTPP] RE: TAZ delineation for CTPP (2006-2010) tabulation SCHEDULE Robert: Well, the ACS data is what it is - can't get around that. The sample size is smaller than that used for the 2000 Decennial Census sample survey (the equivalent of about 12% versus about 16%), so there are indeed many who are dissatisfied with the resulting higher margin of error. This dissatisfaction is probably increased because Census did not report the margin of error until the ACS came along, in the past allowing Census users (myself included) some degree of blissful ignorance of the actual level of uncertainty. At the small area level, notable error rates actually have been in the sample data all along. Whether it will "not be good" at the block group level will depend on how good it has to be for your purposes, and on what data element you are measuring (e.g., smaller percent margin of error for SOV rates than for bicycle commuters). Block groups are of comparable size nationwide, for small communities and large, ranging in the 2000 Census from about 600 to about 3000 and averaging about 1200 (the 2000 Census geography will be that used in the 2005-09 ACS product). The ACS block group data consequently will be of comparable utility for small communities and large, since it is the size of the block group that counts, not the size of the community. One exception to this rule: Census uses higher sampling rates in low population areas (e.g., small towns and small rural counties) so that they can get a large enough sample to achieve statistical significance when they have to report data for small political jurisdictions. Bottom line: for better or worse, ACS 2005-09 block group data is all we will have in the next few months with small area socio-economic and journey-to-work characteristics, unless one has the resources to do one's own surveys. As Ed Christopher pointed out, the 2010 block data also will be available for our use in delineating new TAZs, though it will be limited to basic demographic information, dwelling counts, and owner vs. renter vs. group quarters. Pete Swensson, Senior Planner Thurston Regional Planning Council 2424 Heritage Ct. SW Olympia, WA 98502 (360) 741-2530 (direct line) (360) 956-7575 (main desk) (360) 956-7815 (fax) swenssp(a)trpc.org This e-mail and any attachments are for the use of the addressed individual. If you have received this e-mail in error, please notify our systems manager. TRPC has taken responsible precautions to ensure no viruses are present in this e-mail, however we do not accept responsibility for loss or damage arising from the use of this e-mail or attachments.