ctpp-news May 2005

ctpp-news@mailman.chrispy.net

8 participants
16 discussions

American Community Survey - Frequently Asked Questions

by Chuck Purvis

I'm forwarding this e-mail, with a WORD attachment, from the Census Bureau. This message was sent to the State Data Center listserv. Chuck Purvis, MTC ********************************************************************************************************************************************************* FYI... The American Community Survey is a new nationwide survey designed to provide communities a fresh look at how they are changing. It will replace the long form in future censues and is a critical element in the Census Bureau's reegineered 2010 census plan. Attached are frequently asked questions about the American Community Survey. (See attached file: ACS Media FAQs 5-12.doc) Thanks, Renée Jefferson-Copeland Program Administrator State and Governmental Programs Customer Liaison Office Census Bureau ************************************************************** Charles L. Purvis, AICP Principal Transportation Planner/Analyst Metropolitan Transportation Commission 101 Eighth Street Oakland, CA 94607-4700 (510) 464-7731 (office) (510) 464-7848 (fax) www: http://www.mtc.ca.gov/ Census WWW: http://www.bayareacensus.ca.gov/ **************************************************************

18 years, 11 months

Re: ctpp-news Digest, Vol 17, Issue 3

by Chip Sellers

God Afternoon, I will not be able to attend the meeting in Irvine. Will the materials from the presentation be made available to the rest of us? Thanks, Chip Sellers Associate Planner Stanislaus Council of Governments 900 H Street, Suite D Modesto, CA 95354 (209) 558-4866 (209) 558-7833 FAX csellers(a)stancog.org >>> ctpp-news-request(a)chrispy.net 05/09/05 12:28 PM >>> Send ctpp-news mailing list submissions to ctpp-news(a)chrispy.net To subscribe or unsubscribe via the World Wide Web, visit http://www.chrispy.net/mailman/listinfo/ctpp-news or, via email, send a message with subject or body 'help' to ctpp-news-request(a)chrispy.net You can reach the person managing the list at ctpp-news-owner(a)chrispy.net When replying, please edit your Subject line so it is more specific than "Re: Contents of ctpp-news digest..." Today's Topics: 1. Draft Proposal for Transportation-Related Data Products from ACS for 2004 and Beyond (phillip.a.salopek(a)census.gov) ---------------------------------------------------------------------- Message: 1 Date: Mon, 9 May 2005 15:20:27 -0400 From: phillip.a.salopek(a)census.gov Subject: [CTPP] Draft Proposal for Transportation-Related Data Products from ACS for 2004 and Beyond To: ctpp-news(a)chrispy.net Message-ID: <OF7CC6352E.48D7DC51-ON85256FFC.0066CE0C-85256FFC.006A3E59(a)census.gov> Content-Type: text/plain; charset="us-ascii" I will be delivering a presentation this week in Irvine CA at the Transportation Research Board Conference, "Census Data for Transportation Planning: Preparing for the Future." I've put together a handout to go along with the presentation which outlines the transportation-related content in some new and/or revamped ACS data products. These proposals have not received final approval yet, so are still subject to change. But I've been asked to post them to the listserve to reach a wider audience. The bottom line is that the standard products from ACS will have a lot more tables on the characteristics of workers than have been previously produced in either the ACS or in the decennial census. And for the first time ever, there will be data tabulated by workplace geography in a standard Census Bureau data product. The handout does not cover all products from ACS, just two new types of products ("selected population profiles" and "subject tables") and a major revision to the detailed tables (to be called "base tables" in the future). You should print out the various worksheets to look at them, since there is useful information in the headers and footers that does not show up when you are just looking at the sheet on the screen. --Phil (See attached file: Irvine-Handout_Proposed_ACS_Standard_Tables.xls)

18 years, 11 months

Draft Proposal for Transportation-Related Data Products from ACS for 2004 and Beyond

by phillip.a.salopek＠census.gov

I will be delivering a presentation this week in Irvine CA at the Transportation Research Board Conference, "Census Data for Transportation Planning: Preparing for the Future." I've put together a handout to go along with the presentation which outlines the transportation-related content in some new and/or revamped ACS data products. These proposals have not received final approval yet, so are still subject to change. But I've been asked to post them to the listserve to reach a wider audience. The bottom line is that the standard products from ACS will have a lot more tables on the characteristics of workers than have been previously produced in either the ACS or in the decennial census. And for the first time ever, there will be data tabulated by workplace geography in a standard Census Bureau data product. The handout does not cover all products from ACS, just two new types of products ("selected population profiles" and "subject tables") and a major revision to the detailed tables (to be called "base tables" in the future). You should print out the various worksheets to look at them, since there is useful information in the headers and footers that does not show up when you are just looking at the sheet on the screen. --Phil (See attached file: Irvine-Handout_Proposed_ACS_Standard_Tables.xls)

18 years, 11 months

CTPP Part 3 Issues - Anniversary Report (long post, with small attachment)

by Chuck Purvis

TO: CTPP-News: FR: Chuck Purvis, MTC RE: CTPP Part 3 Issues On the one-year anniversary of receiving the Census 2000 CTPP Part 3 data, I thought I would re-release an old e-mail looking at the Part 3 data suppression and data loss issues (with some current observations). There are 14 total tables in the CTPP Part 3 area-to-area "flow"data. Five of these tables (3-3 through 3-7) have a minimum 3-worker sample threshold applied. If there are less than 3 sample workers, total, on an area-to-area basis, then values for that flow interchange are suppressed. This can have a significant impact at finer geographic summary levels, e.g., tract-to-tract, zone-to-zone, and block group-to-block group. (This is not 'new' news, but is old, bad news.) This particular data analysis is for the Part 3 data for intra-San Francisco Bay Area. Other regions of various sizes will probably show similar patterns. Attached is my "bottom line" spreadsheet that shows the data loss due to suppression and rounding error across all geographic summary levels. Table 3-1 problems are limited solely to rounding errors. There are insignificant rounding errors going from the county-to-county to the place-to-place geographic summary levels, but modest rounding errors at the tract-to-tract level (a loss of 1.5%) and an incredible rounding loss of 3.5 percent at the zone-to-zone level. Note that rounding is done on an interchange cell by interchange cell basis. There is no "bucket rounding" applied in the CTPP to correct for this rounding error. Table 3-2 (household workers by means of transportation) also shows a similar rounding error problem, topping out at a 4.2 percent loss due to rounding at the zone-to-zone level. Table 3-6, all workers by detailed means of transportation, shows minor data loss due to rounding and suppression at the place-to-place level (-1.2 percent), but major data losses at the tract-to-tract level (-34.4 percent), and zone-to-zone level (-71.5 percent). Yes, 71.5 percent of the detailed means of transportation is lost at the zone-to-zone level. The only usable information from Table 3-6, at the zone-level, is the number of at home workers (Table 3-6, cell 18.) (NOTE: If you need block group or tract level workers working AT HOME, USE SUMMARY FILE #3 DATA!!!) The CTPP Part 3 does NOT have an "all workers universe" table on workers by DETAILED means of transportation, WITHOUT the sample size threshold. On the other hand, we can derive "all workers by means of transportation" by dividing the "aggregate travel time by means" (Table 3-14) by the "average travel time by means" (Table 3-8). This "back door" approach to estimating workers by means of transportation (universe: all workers) works exceptionally well. There is basically a negligible data loss across all geographic summary levels. For the past year we have been working with this "derived" commuters, zone-to-zone, based on dividing Table 3-14 by Table 3-8. This is essential if you're examining commuter flows, average commute distances (in miles or kilometers) and commute length frequency distributions. One problem with the Table 3-14 / 3-8 commuters is the "Other" category which combines five sub-groups: bicycle, walk, motorcycle, taxicab, and "other means". What this really means is that we (and probably all others in the U.S.) will be unable to create zone-to-zone bicycle or walk commuter matrices. (This is unlike the 1990 Census, where we created zone-to-zone bicycle and walk commuter matrices for purposes of analyzing commute distances and commute distance frequency distributions for these non-motorized commute modes....) (Actually, the Part 3 data came too late (May 2004) to be used in our travel demand model validation efforts, which we completed April 2004. We used the county-to-county flow data, derived from the 5% PUMS, by means of transportation by household income quartile, for validating our work trip distribution and work trip mode choice models.) That's all I have to offer for the moment. Think it over, and hope to see folks at the Census / Transportation Conference in Irvine, CA this week! Chuck Purvis, MTC ************************************************************** Charles L. Purvis, AICP Principal Transportation Planner/Analyst Metropolitan Transportation Commission 101 Eighth Street Oakland, CA 94607-4700 (510) 464-7731 (office) (510) 464-7848 (fax) www: http://www.mtc.ca.gov/ Census WWW: http://www.bayareacensus.ca.gov/ **************************************************************

18 years, 11 months

CTPP Status Report, April 2005

by Srinivasan, Nanda

All- Attached is the latest (April 2005) CTPP Status Report. The report provides some learning tips on the American Community Survey, the use of the CTPP Access Tool for Part 3, and the use of the BTS TranStats website for downloading CTPP 2000 data. Since the publication of the report, the TranStats team have completed posting Part 2 data (Place of Work) into their system, along with Part 1 (Place of Residence), and Part 3 (Journey-to-Work Flow). Hope to see some of you at the "TRB Census Data for Transportation Planning: Preparing for the Future" conference in Irvine next week! Thank you, Nanda Srinivasan

18 years, 12 months

RE: County-level ACS

by Murakami, Elaine

Dear Garth-- I am going to answer and include the CTPP listserv. Thanks for the timely query. The release of data from the ACS is based on the population of the area, so you will not get "all counties" in Michigan at the same time. So, Counties with population greater than 250,000 have annual data (2003) already available at: http://factfinder.census.gov/servlet/DatasetMainPageServlet?_program=ACS <http://factfinder.census.gov/servlet/DatasetMainPageServlet?_program=ACS&_l…> &_lang=en&_ts=133099923308 These are from the Supplemental Survey component of the ACS during it's test phase. The data from 2005 ("full implementation") should be available in mid-2006. Counties with population over 65,000 will have data from 2005 released in 2006. Counties with population over 20,000 will require a 3-year accumulation of data, so data from 2005/06/07 will be required, and will not be released until 2008. Anything with less than 20,000 population will require 5-years of data accumulation before release. Also, we have EXCELLENT news from the CB. The CB has DRAFT tables for ACS including many relevant tables for transportation planners. There are many "CTPP-like" tables by "Means of Transportation to Work" at both residence geography AND workplace geography (but not FLOW) as part of the standard tabulation package, particularly as compared to SF3 from Census 2000. Phil Salopek of the CB will be sending these DRAFTs out to the CTPP listserv later this week. They were distributed in paper copy at the TRB Planning Applications conference in Portland last week. Phil expects this table structure to be used starting with the 2004 data (limited to large geographic areas). Elaine Murakami FHWA Office of Planning 206-220-4460 (Seattle) -----Original Message----- From: Garth Banninga [mailto:banningag@michigan.gov] Sent: Monday, May 02, 2005 6:54 AM To: Murakami, Elaine Subject: County-level ACS Hi Elaine: Now that all counties are part of the ACS annual sample, when can I expect to see ACS data for all Michigan counties on the ACS's data tables links? Thanks, Garth Banninga, Planner MDOT-Planning 517.335.2959

18 years, 12 months

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ctpp-news May 2005