New subject: CTPP Update - Another Question

11 Jun 2008

On May 21 and June 4 members of the CTPP team conducted a series of
webinars to help bring our community up-to-speed on several of the CTPP
activities.  The slides from these presentations can be downloaded from
our webinar room at http://fhwa.acrobat.com/ctpp1 (enter as a guest) and
the responses to many of the questions asked during the meetings are
presented below.  If folks have additional questions please feel free to
post them to the list serve and someone on the CTPP team will attempt to
answer them.

CTPP Webinar - Questions and Answers

Question: Will the 3-year CTPP data product based on ACS include tables
by race and household income?
Response:  Yes but the best source for information on race will still be
the Census Bureau's standard ACS tabulations found on American
FactFinder (http://factfinder.census.gov/).  The 3-year CTPP proposed
tables for parts 1 and 2 include a few tables with the variable
"minority status." Also, there are various tables with the variables -
Income, Poverty Status and Worker Earnings that will be available.
Please note that Poverty Status is a calculated variable based on
household income, family size, number of children and number of family
members over the age of 65.

Question: Since the new CTPP products will be based on data collected
over 3 years (or 5 years), to which year will the income be adjusted?
Response:  Income will be adjusted to the last year of the survey
period.   For the first 3-year product all incomes will adjusted to
2007.

Question: Is there data available on zero car households? If yes, what
geography level is it available?
Response:  Yes, there will be information available for zero car
households in both the 3-year CTPP data product and as part of the
standard Census products.  The data will be available for geographic
areas greater than 20,000 residents.

Question: Slides 6 & 7 of the DRB presentation show different
percentages of data lost due to DRB rules, why is that?
Response:  Slide 6 showed the number of workers lost while slide 7
showed the number of origin-destination pairs lost.  The point is that
when thresholds were applied to CTPP Part 3 data as was the case with
the 2000 data, many folks looked at the loss of workers as being
significant but more surprising was actual loss of individual O-D
pairs.  All in all table thresholds devastated the part 3 flow data.   

Question: 2005 ACS data doesn't have information on Group Quarters, but
the 2006 and 2007 do.  How is this being handled in the 3-year 2007 ACS
products?
Response:  The Group Quarter data available for 2 years (2006 and 2007)
will be reweighed to account for the missing year.

Question: Will the variable - Means of Transportation to Work have walk
and bike modes combined? Also, what about taxi, bus and other?
Response:  Regarding the 3-year CTPP data product there are multiple
category lists for the variable - Means of Transportation to Work. 
There are a few tables all 17 modes plus the total are shown separately
but then there are many others where walk and bike have been collapsed
together.  A great deal of the detail on the mode variable is in the
hands of the Census Bureau's disclosure Review Board.  Currently they
have proposed some very tight restrictions on the proposed 3-year CTPP
tables.  Please see http://trbcensus.com/drb/ for more 

Question: Do you have anything on the TAZ definition timeframe that you
can share with the group?
Response:  Please see our Status Report newsletter for the latest
http://www.TRBcensus.com/newsltr/sr052008.pdf.

Question: Can you talk about the difference in income between ACS and
Long Form?
Response:  In Census 2000, the question was asked during April for the
previous year, 1999.  Because April is so close to IRS annual return
data it was felt that "good" income data was being collected because it
was fresh in people's minds.  However, for the ACS the same questions
are asked, but the respondent could be getting the survey during any
month of year (depending on when she/he received the form).  This
reported income is then adjusted to the current year (year of
tabulation) based on CPI.  There are several issues with this with the
largest being that at anytime during the year most people do not how
much money they made in the last 12 months.  Needless to say the income
question is messy.

Question: Poverty rates seem discontinuous, higher. Any ideas why?
Response:  Yes, they are discontinuous.  Hopefully they will look better
with the 3-year ACS data products.

Question: If the DRB is so strict with its rules then why bother with
new TAZs?
Response:  We hope that the DRB will relax its rules but having TAZs
that correspond to the ACS data release products (65,000 pop TAZs,
20,000 pop TAZs and small TAZs) will help us in the future all sorts of
data products.  Having geography match the data release seems to make
good sense so that we can at least get complete coverage (wall-to-wall)
within a region.

Question: What are the implications of rising fuel prices on travel
choices on mode to work?  Has anybody thought about it, especially with
aggregating 3 years worth of data?  Since the ACS asks about "usual"
mode, it could still miss modes used only part of the time. 
Response:  The 3 year ACS trend data might look a lot different than the
2000 data. This might be a good research question.

Question: Is the category list for the variable - occupation being
consolidated?
Response:  No, DRB has not asked us to collapse the variables - industry
or occupation.

Question: Is anybody planning to write to Congress about the DRB issue? 
Response: AASHTO SCOP is sending a letter to the Census Bureau to appeal
the DRB decision.  As FHWA staff, we cannot contact Congress directly
but we know that many regional agencies do talk with their Congressional
delegations.  It is somewhat ironic but many of the congressionally
mandated analysis like the FTA New Starts program and environmental
justice analysis all need data at a smaller geography level which will
be difficult to obtain with the DRB's current rules.
Question: We are relatively a new MPO and I have a CTPP 101 question. 
As an MPO do we need to provide you any information, and what are our
sources of information regarding CTPP specifically regarding TAZs?
Response: The CTPP listserve is a good place for information regarding
ongoing CTPP related activities. The TAZ definition process is planned
for March/April of 2009 and it is recommended that MPO's allocate some
budget when preparing their work plans for FY 2009, especially for new
MPOs. The CTPP Status Report is also a good source of information.  If
you have any particular questions please do not hesitate to contact
anyone one of us on the CTPP team.

Question:  Somewhere it was noted the first CTPP ACS product would be
available in 2009 for areas of 20,000 or more for places and counties.  
Response: Yes that is correct.  We are still in the negotiation stage
regarding some DRB issues but this is our GOAL.  This first CTPP product
would use 3 years of ACS
data.   

Question:  There was also a mention of TAZ level data also for 20,000
population threshold.  However, I am not sure if this is included in the
first 3 year product for 2009, or whether the first TAZ level report
will not be available until 2012 with a 5 year product.
Response: To get "small" area geography like a TAZ or a census tract,
the census requires 5 years of ACS data. So, we are planning to wait for
2006 thru 2010 ACS data to incorporate 2010 Census geography and
weights, which we hope would be tabulated by 2012.   This will likely
require some data synthesis before release.  Because of the probability
that the data will be synthetic, we do not anticipate any population
threshold.  

-- 
Ed Christopher
Resource Center Planning Team
Federal Highway Administration
19900 Governors Drive
Olympia Fields, Illinois  60461
708-283-3534 (V)  708-574-8131 (cell)
708-283-3501 (F)