17 May
2013
17 May
'13
4:37 p.m.
Hi Jonathan,
Some excellent observations, thanks for sharing.
An example of one of the underlying strengths of CTPP is that even though CTPP 2000 flow
data is now 13 years old, the journey-to-work data still represents the "best
available" data across the country, for use in home-based work regional travel model
validation checks. I am not referring to simple HBW trip length frequency checks (for
which much smaller samples, e.g., the samples available from typical household surveys), I
am talking about district-to-district checks of predicted versus observed HBW person trips
by (let's say) 0-vehicle, 1-vehicle and 2+ vehicle socioeconomic groups. Yes, the
"observed" data is getting old, but can be "fratared" with the growth
rates in population and employment to be a reasonably good representation of "current
year" HBW flows. Many people think travel forecasts are way off from reality because
of problems with the mode choice model and/or traffic assignment procedures, but I wonder
how often the real "problem" can be traced back to trip (or activity) generation
and the prediction of the zone-to-zone person trip (or activity flow) tables!
The next "best available" dataset of home-to-work commuter trips is going to be
the next available "five-year" CTPP, that is now very close to a public release.
There will of course be concerns that the overall number of raw records in the new
"five-year" CTPP is a lot less than what was obtained in CTPP 2000, but all that
really means, I think, is that one must be very careful to never rely on the actual
TAZ-to-TAZ numbers: but still feel very confident with the prudent aggregation of
TAZ-to-TAZ numbers into locally meaningful district-to-district totals. In regards to the
national sample, the new CTPP will still be a pretty huge number of records, compared to
just about anything else that is not some type of "private" purchasable
database. It would be a shame if the about-to-be-released set of CTPP-based TAZ-to-TAZ
flows is the last one ever produced. If the NHTS sample size could come anywhere close to
the CTPP sample size, then maybe one wouldn't need the CTPP, but that is not going to
ever happen.
Ken Cervenka
FTA Office of Planning and Environment
From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of
Jonathan Lupton
Sent: Friday, May 17, 2013 3:36 PM
To: ctpp-news(a)chrispy.net
Subject: [CTPP] The Case for ACS, the Economic Census, sampling and Federal
data-gathering
The loss of Census sampling (today the ACS), the Census of Agriculture, the Economic
Census, etc., would be disastrous in so many ways I find it hard to believe anyone - even
deeply partisan politicians - would advocate their demise. The small gain to the Federal
government's bottom line would be undercut by huge (albeit hidden) losses to the
private and public sectors. The loss would be especially acute for small businesses.
1. There can be no serious doubt that Federal sample products leverage their cost
many times over in benefits to the economy. The benefits are so widespread, and so
implicit, that the burden of proof must lie on anyone attempting to undo Federal
data-gathering. And they will find no such proof.
2. The U.S. government has, in the past, set the world standard for data-gathering.
The widespread availability of free, accurate data runs hand-in-hand with upholding the
standard as the world's foremost democratic society. To surrender the ACS and related
products is not just a bad idea, it is a retreat from leadership.
3. Answering ACS forms, or any other Federal questionnaire, is a matter of personal
responsibility. To survive, democracy depends not just on the protection of personal
rights; it also demands a sense of responsibility by its citizens.
4. I have never heard of anyone going to prison, or even being fined, for failing to
provide data to Census takers. Everyone knows that there are people and businesses which
refuse to cooperate; the practice of non-compliance is already tolerated. But compliance
is the law, and this sets a tone of legality which allows the ACS and other projects to
gather the necessary data.
5. If the data business becomes mostly private in nature, the cost of obtaining data
will largely limit its availability to large corporations that could afford to purchase
it, creating another disadvantage to small businesses and business start-ups.
6. Here in Little Rock we host one of the country's largest data-gathering
agencies, the Acxiom Corporation. It's an open secret that Acxiom, and other
companies like it, hold vast amounts of data about just about everybody. While Census data
is protected by confidentiality laws, disturbingly intimate corporate data can be sold to
the highest bidder.
7. While the anti-census anti-government lobby argues unconvincingly about
government as "Big Brother," there is therefore another, less accountable
version of "Big Brother," existing in secret corporate data-gathering. Such data
could become the only basis for information about our society. Without Federal laws, and
Executive and Congressional oversight, who could prevent this private data from being
falsified? Without the credibility of ACS and related programs as a
"cross-check," false information could be fed into the system, and could be
manipulated by private power brokers.
8. Here in Little Rock we have a small spinoff company which has used Acxiom data to
attempt census-like products. Around 2009, they privately gave me a total for the
state's largest county (Pulaski) that disagreed with my careful estimates. They ended
up being high by about 7 percent, compared with the Census 2010 count that appeared a few
months later. My own estimate, based on housing records, was within 1 or 2 percent. A
corporate representative thought their figures were inarguably correct; I thought their
methods for counting people were flawed. Guess who was right.
9. Data-gathering by the Census Bureau and related agencies isn't perfect, but
it has oversight through the democratic process. I'll trust a process that's been
around since 1790 before I trust a private company that answers first to shareholders.
It is my earnest hope that the effort to kill the ACS is so blatantly foolish that it will
never make it to a vote by the U.S. Congress or Senate. I ask those who keep their ear to
Congress to please keep the data community well-informed about this disturbing
development.
Jonathan Lupton AICP
Research Planner
Metroplan
Little Rock, Arkansas
501-372-3300