[CTPP] Re: ctpp-news Digest, Vol 62, Issue 9
Patty Becker
pbecker at umich.edu
Mon Apr 20 10:46:29 CDT 2009
I agree completely. We use tracts only (1) in thematic maps with
broad categories, or (2) for aggregation. This goes for all uses of
ACS data, not just CTPP.
Patty Becker
At 07:50 PM 4/16/2009, you wrote:
>Todd Graham makes all the right points. CTPP is statistically very
>thin (and IMO not usable at any fine granularity such as CT, let alone TAZ).
>
>Keith
>
>On Wed, Apr 15, 2009 at 1:16 PM,
><<mailto:ctpp-news-request at chrispy.net>ctpp-news-request at chrispy.net> wrote:
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>Today's Topics:
>
> 1. RE: RE: Census Bureau Federal Register Notice on New
> DataDisclosure Restrictions (Michael Moan)
> 2. remove (Brian Raimondo)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Wed, 15 Apr 2009 14:42:30 -0400
>From: "Michael Moan" <<mailto:MMoan at doa.ri.gov>MMoan at doa.ri.gov>
>Subject: RE: [CTPP] RE: Census Bureau Federal Register Notice on New
> DataDisclosure Restrictions
>To: <<mailto:ctpp-news at chrispy.net>ctpp-news at chrispy.net>
>Message-ID: <<mailto:s9e5f27d.037 at ri.gov>s9e5f27d.037 at ri.gov>
>Content-Type: text/plain; charset=US-ASCII
>
>Yes this is too much and one of the reasons I opted out last time.
>
>
> >>> <mailto:JSabula at rideuta.com>JSabula at rideuta.com 4/15/2009 1:38 PM >>>
>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: <mailto:ctpp-news-bounces at chrispy.net>ctpp-news-bounces at chrispy.net
>[mailto:ctpp-news-bounces at chrispy.net] On Behalf Of Agnello, Paul
>Sent: Wednesday, April 15, 2009 10:22 AM
>To: Ed Christopher; Graham, Todd; Penny Weinberger;
><mailto:ctpp-news at chrispy.net>ctpp-news at chrispy.net
>Cc: Memmott, Jeff <RITA>;
><mailto:kcooper at dot.state.nv.us>kcooper at dot.state.nv.us;
><mailto:amy.thomas at ky.gov>amy.thomas at ky.gov;
><mailto:robbins at wsdot.wa.gov>robbins at wsdot.wa.gov; Murakami,Elaine;
><mailto:ayalew.adamu at dot.ca.gov>ayalew.adamu at dot.ca.gov;
><mailto:sandy.beaupre at dot.state.wi.us>sandy.beaupre at dot.state.wi.us;
><mailto:willimasjs at dot.state.al.us>willimasjs at dot.state.al.us;
><mailto:bobbi.retzlaff at dot.state.wi.us>bobbi.retzlaff at dot.state.wi.us;
><mailto:dhardy at ampo.org>dhardy at ampo.org;
><mailto:nerlbaum at dot.state.ny.us>nerlbaum at dot.state.ny.us;
><mailto:donna.weaver at po.state.ct.us>donna.weaver at po.state.ct.us;
><mailto:pleasantmd at scdot.org>pleasantmd at scdot.org;
><mailto:huiwei.shen at dot.state.fl.us>huiwei.shen at dot.state.fl.us;
><mailto:kmiller at njtpa.org>kmiller at njtpa.org;
><mailto:rdenbow at ampo.org>rdenbow at ampo.org;
><mailto:Ron.fields at arkansashighways.com>Ron.fields at arkansashighways.com;
><mailto:jonette.kreideweis at dot.state.mn.us>jonette.kreideweis at dot.state.mn.us;
><mailto:nsrinivasan at nas.edu>nsrinivasan at nas.edu;
><mailto:phil.mescher at dot.state.ia.us>phil.mescher at dot.state.ia.us;
>Curling,Samuel F.; Weiner,Ed <OST>;
>Pickard, Andy,P.E.;
><mailto:virginia.porta at arkansashighways.com>virginia.porta at arkansashighways.com;
>Tambellini,
>Rick L.; Fred at NARC.org
>Subject: [CTPP] RE: Census Bureau Federal Register Notice on New
>DataDisclosure Restrictions
>
> >From a state planning perspective, I think it is very disappointing
>(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 at VDOT.Virginia.gov
>Website: <http://www.virginiadot.org/>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 at berwyned.com]
>Sent: Wednesday, April 15, 2009 12:07 AM
>To: Graham, Todd; Penny Weinberger
>Cc: Murakami, Elaine; Agnello, Paul;
><mailto:banningag at michigan.gov>banningag at michigan.gov;
><mailto:sandy.beaupre at dot.state.wi.us>sandy.beaupre at dot.state.wi.us;
><mailto:kcooper at dot.state.nv.us>kcooper at dot.state.nv.us;
><mailto:jonette.kreideweis at dot.state.mn.us>jonette.kreideweis at dot.state.mn.us;
><mailto:phil.mescher at dot.state.ia.us>phil.mescher at dot.state.ia.us;
><mailto:ayalew.adamu at dot.ca.gov>ayalew.adamu at dot.ca.gov;
><mailto:pleasantmd at scdot.org>pleasantmd at scdot.org;
><mailto:virginia.porta at arkansashighways.com>virginia.porta at arkansashighways.com;
><mailto:bobbi.retzlaff at dot.state.wi.us>bobbi.retzlaff at dot.state.wi.us;
><mailto:robbins at wsdot.wa.gov>robbins at wsdot.wa.gov;
><mailto:huiwei.shen at dot.state.fl.us>huiwei.shen at dot.state.fl.us;
><mailto:amy.thomas at ky.gov>amy.thomas at ky.gov;
><mailto:donna.weaver at po.state.ct.us>donna.weaver at po.state.ct.us;
><mailto:willimasjs at dot.state.al.us>willimasjs at dot.state.al.us;
><mailto:sharon.ju at h-gac.com>sharon.ju at h-gac.com;
><mailto:kmiller at njtpa.org>kmiller at njtpa.org; Pickard, Andy, P.E.;
><mailto:creschovsky at mwcog.org>creschovsky at mwcog.org;
><mailto:grousseau at atlantaregional.com>grousseau at atlantaregional.com;
>Fred at NARC.org;
><mailto:rdenbow at ampo.org>rdenbow at ampo.org;
><mailto:dhardy at ampo.org>dhardy at ampo.org;
><mailto:rmccready at aashto.org>rmccready at aashto.org; Memmott,
>Jeff <RITA>; <mailto:nsrinivasan at nas.edu>nsrinivasan at nas.edu;
>Weiner, Ed <OST>;
><mailto:Ron.fields at arkansashighways.com>Ron.fields at arkansashighways.com;
><mailto:nerlbaum at dot.state.ny.us>nerlbaum at 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:
> > State and MPO colleagues--
> >
> > Discussions about Census data disclosure have been making the rounds.
> I wanted to share a few thoughts with the SCOP Census Data Work
>Group...
> >
> > Re: protecting the individual confidentiality of respondents. True,
>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.
> >
> > We know ACS sampling is thin (1 in 8 households surveyed, 60-65%
>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.
> >
> > I know some members of SCOP have been drafting comments in response
>to 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?
> >
> > As a statistician, I disagree - and I think there are creative
>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.
> >
> > Sorry to bring this up, but here goes: AASHTO SCOP should revisit
>the 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??
> >
> > I know there are sunken costs already. Still, my candid advice:
>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.
> >
> > I understand that people are up-at-arms about this. (Census Bureau,
>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.
> >
> > -- Todd Graham
> >
> >
> >
> > ________________________
> >
> > Todd Graham
> > Principal Forecaster
> > Metropolitan Council
> > 390 Robert Street North
> > Saint Paul, MN 55101
> >
> > phone 651/602-1322
> > email <mailto:todd.graham at metc.state.mn.us>todd.graham at metc.state.mn.us
> > web <http://www.metrocouncil.org>www.metrocouncil.org
> > www.metrocouncil.org/metroarea/stats.htm
> > ________________________
> >
> >
> >
>
>--
>Ed Christopher
>708-283-3534 (V)
>708-574-8131 (cell)
>
>FHWA RC-TST-PLN
>19900 Governors Dr
>Olympia Fields, IL 60461
>
>
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>
>------------------------------
>
>Message: 2
>Date: Wed, 15 Apr 2009 15:41:36 -0400
>From: "Brian Raimondo" <<mailto:braimondo at swfrpc.org>braimondo at swfrpc.org>
>Subject: [CTPP] remove
>To: <<mailto:ctpp-news at chrispy.net>ctpp-news at chrispy.net>
>Message-ID:
>
><<mailto:51C7115D89DD7F4FA0D991DBE96511837493D9 at exchange.corp.swfrpc.org>51C7115D89DD7F4FA0D991DBE96511837493D9 at exchange.corp.swfrpc.org>
>Content-Type: text/plain; charset="us-ascii"
>
>Please remove me from all the mailing lists.
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>End of ctpp-news Digest, Vol 62, Issue 9
>****************************************
>
>
>
>
>--
>Keith Lawton
>503 538 6509
>503 453 7630 (mobile)
>_______________________________________________
>ctpp-news mailing list
>ctpp-news at 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 at umich.edu
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