Friends of the Census: This group would work much more efficiently if it had a normal internet forum structure. A forum isn't very hard to establish and would allow us to discuss the various issues without having to send emails to everybody all the time. -----Original Message----- From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Sabula,Julianne Ruth (Engineering-Const Planner II) Sent: Wednesday, April 15, 2009 10:38 AM To: ctpp-news(a)chrispy.net Subject: RE: [CTPP] RE: Census Bureau Federal Register Notice on NewDataDisclosure Restrictions Is there a way to reply just to the person you are conversing with? I would rather access these messages on the discussion board if I'm interested than empty my inbox once an hour. Julianne Sabula Utah Transit Authority -----Original Message----- From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces(a)chrispy.net] On Behalf Of Agnello, Paul Sent: Wednesday, April 15, 2009 10:22 AM To: Ed Christopher; Graham, Todd; Penny Weinberger; ctpp-news(a)chrispy.net Cc: Memmott, Jeff <RITA>; kcooper(a)dot.state.nv.us; amy.thomas(a)ky.gov; robbins(a)wsdot.wa.gov; Murakami,Elaine; ayalew.adamu(a)dot.ca.gov; sandy.beaupre(a)dot.state.wi.us; willimasjs(a)dot.state.al.us; bobbi.retzlaff(a)dot.state.wi.us; dhardy(a)ampo.org; nerlbaum(a)dot.state.ny.us; donna.weaver(a)po.state.ct.us; pleasantmd(a)scdot.org; huiwei.shen(a)dot.state.fl.us; kmiller(a)njtpa.org; rdenbow(a)ampo.org; Ron.fields(a)arkansashighways.com; jonette.kreideweis(a)dot.state.mn.us; nsrinivasan(a)nas.edu; phil.mescher(a)dot.state.ia.us; Curling,Samuel F.; Weiner,Ed <OST>; Pickard, Andy,P.E.; virginia.porta(a)arkansashighways.com; Tambellini, Rick L.; Fred(a)NARC.org Subject: [CTPP] RE: Census Bureau Federal Register Notice on New DataDisclosure Restrictions (whether it is due to new tighter disclosure rules or the statistical reliability issue) that it appears that states and MPOs will not have the same quality of CTPP data available in 2010 as in 2000 and previous census cycles. Particularly since states are paying considerably more for the next CTPP than for 2000. Virginia's share more than tripled in cost from 2000 to 2010. I agree with the earlier point that if states are paying for the special tabulations, there should not be these new disclosure restrictions governing the release of the data. I am not clear on why the disclosure restrictions are even an issue since I am not aware of any past disclosure issues with the 2000 or prior CTPP and mining CTPP data would not appear to be a particularly effective way for someone to try to find out personal info. about someone else. If this is such an issue, why was it not a problem in the past? While it may be too late to fix the problems associated with data quality/content for the next CTPP, I'm wondering if there are ways that the ACS sample could be increased with additional federal and/or state support in the future so that this statistical reliability issue could be addressed, perhaps in a process similar to the way NHTS is done, or perhaps CTPP data needs to come from a different source long term if the ACS data is not reliable enough to meet state and metropolitan planning needs. Decision makers increasingly want to see more robust technical tools and analysis which to support planning analysis which requires more detailed data at the small area from sources such as ACS, CTPP, NHTS, etc., and major conferences, e.g., TRB, and federal agencies have supported better data for transportation planning for years. Therefore, from a state perspective, the Census Bureau's proposed policy change run counter, not only to prevailing trends, but to the policies from other federal transportation agencies. ------------------------------------------- Paul T. Agnello Travel Demand Modeling Manager Virginia Department of Transportation Transportation & Mobility Planning Division 1401 East Broad Street Telephone (804) 786-2531 Richmond, Virginia 23219-2000 Fax (804) 225-4785 E-mail: mailto:paul.agnello(a)VDOT.Virginia.gov Website: http://www.virginiadot.org/ * CONFIDENTIALITY/PRIVACY NOTICE - The documents included in this transmission may contain information that is confidential and/or legally privileged. If you are not the intended recipient, or the employee or agent responsible for delivering the information to the intended recipient, you are hereby notified that any disclosure, copying, distribution, or action taken in reliance on the contents of these documents is strictly prohibited. If you have received this document in error, please notify the sender immediately to arrange for return or destruction of these documents. -----Original Message----- From: Ed Christopher [mailto:edc(a)berwyned.com] Sent: Wednesday, April 15, 2009 12:07 AM To: Graham, Todd; Penny Weinberger Cc: Murakami, Elaine; Agnello, Paul; banningag(a)michigan.gov; sandy.beaupre(a)dot.state.wi.us; kcooper(a)dot.state.nv.us; jonette.kreideweis(a)dot.state.mn.us; phil.mescher(a)dot.state.ia.us; ayalew.adamu(a)dot.ca.gov; pleasantmd(a)scdot.org; virginia.porta(a)arkansashighways.com; bobbi.retzlaff(a)dot.state.wi.us; robbins(a)wsdot.wa.gov; huiwei.shen(a)dot.state.fl.us; amy.thomas(a)ky.gov; donna.weaver(a)po.state.ct.us; willimasjs(a)dot.state.al.us; sharon.ju(a)h-gac.com; kmiller(a)njtpa.org; Pickard, Andy, P.E.; creschovsky(a)mwcog.org; grousseau(a)atlantaregional.com; Fred(a)NARC.org; rdenbow(a)ampo.org; dhardy(a)ampo.org; rmccready(a)aashto.org; Memmott, Jeff <RITA>; nsrinivasan(a)nas.edu; Weiner, Ed <OST>; Ron.fields(a)arkansashighways.com; nerlbaum(a)dot.state.ny.us Subject: Re: Census Bureau Federal Register Notice on New Data Disclosure Restrictions Todd--You should have posted to the full CTPP listserve. You make all good points that people need to think about. One point of clarification is that the AASHTO CTPP Oversight Board has sent a new proposal of tables over to the CB for 3-year data and in fact the mode to work questions are rolled up. I believe the largest roll-up is 3 modes: auto, other and total. I took on the task of posting the new tables to the Listserve but haven't done so yet. The tables are still fresh off the press and I will not be able to get to it till Thursday. One point that is missed in all of this is that with the 3-year data we are talking about a zone system with 20,000 people per zone. That is the size of 7 or so tracts. Pretty big when you are talking about planning within a region. Even though you are right about the statistical quality of the data the CB is not telling us there is a statistical reason for suppressing the data. They are basing it solely on disclosure requirements. Disclosure requirements and arguments that can not be proven. Another point that is missed is that the old long form data suffered from the same relative thinness at the tract, block group and TAZ level. At those levels of geography many of the same tables that are not passing the disclosure rules now would not have passed then. Yes, the data today is a little thinner but that has never been the issue. One last point is that CTPP has always been a special tabulation and if you push the issue far enough logic should dictate that someone purchasing a special tabulation should be allowed to buy whatever data they want no matter how crappy it is. In 1980 the CB used to sell us the data with a "caveat emptor" sticker on it. Putting all the cards on the table does point to why synthetic data for small area analysis is so important. Unfortunately there are not only statistical issues of methodology to deal with but also practical issues of political acceptance within the community. Graham, Todd wrote: I wanted to share a few thoughts with the SCOP Census Data Work Group... the Bureau itself is standing this up as their decision basis (it's a legally powerful position). But I think the larger, latent, real concern among the Bureau statisticians is statistical reliability. response rates?) and temporally spread out... And we know there will be large numbers of individual data cells in the planned CTPP-from-ACS tabs where estimates would be based on just 1 or 2 respondents. As a statistician, I really don't like this. Resulting estimates are not robust. (There's great uncertainty around whether the 1 or 2 survey respondents should represent 10-20 other people - or perhaps, by freak luck, the 1 or 2 persons are unique. There is real probability of 1 or 2 respondents being *not* representative.) This is particularly true in the most highly-detailed crosstabs. Hundreds of cells in a table *will* result in many cells with small numbers. the Fed Register Notice. Some of these comments will make emphatic proposals that we must have fully populated CTPP tables. I worry that this line of reasoning won't have much traction at Census Bureau... And really, do we believe that any numbers (regardless of statistical reliability) are better than no numbers? alternatives that are viable: (1) SCOP and Census Data Workgroup have discussed data synthesis techniques to simulate or synthesize the desired details. Or (2), a more conventional solution, more highly aggregated ("rolled up") categorization in the CTPP-from-ACS tabs. What SCOP requested in 2007 looks a lot like CTPP 2000 -- even though we knew that ACS Survey sampling is thinner than Census 2000. CTPP-from-ACS design, reopen it for discussion, go back to the drawing board, and consider more highly aggregated ("rolled up") categorizations in the CTPP-from-ACS tabs. Do we really need 10 (or 17) categories of mode of travel (can we live with fewer)? Do we really need 25 categories of household income (can we live with fewer)? Do we really need tabs with travel-start-time expressed in 15-minute intervals?? AASHTO SCOP and other funding partners in the CTPP need to take a deep breath... and consider revising the special tabs requests. And Census Bureau should cooperate and enable such a new plan. for their part, waited until 2008 to clearly signal that there would be a tighter data disclosure regime than experienced in CTPP 2000...) But the realpolitic is: Census Bureau statisticians have already decided this matter -- isn't the Fed Register notice just a formality? -- and from the standpoint of good statistical science, their decision is right. -- Ed Christopher 708-283-3534 (V) 708-574-8131 (cell) FHWA RC-TST-PLN 19900 Governors Dr Olympia Fields, IL 60461 _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news _______________________________________________ ctpp-news mailing list ctpp-news(a)chrispy.net http://www.chrispy.net/mailman/listinfo/ctpp-news