Elaine,
To answer your question, the "Journey to Work Trends" is useful to me,
but I would prefer that it be done "decennially" (and rigorously),
adding 2010 (perhaps via an average of 2009-2011 data) to the previous
years (1960, 1980, 1990, 2000), providing consistent 10-year time gaps.
Rob
>>> Elaine.Murakami(a)fhwa.dot.gov 10/1/2008 5:17 PM >>>
Hi Everyone -
I bet you have a lot of questions about CTPP using the first 3 years
of
ACS and TAZs, but unfortunately, I can't answer them yet!
Given the current uncertainty of the next CTPP ("custom tabulation")
using the ACS, we are moving forward to develop products using
standard
ACS products. Some of you will recall that we created a series using
the first 2005 ACS data products. They are posted on both the FHWA
web
http://www.fhwa.dot.gov/planning/census/2005tpoverview.htm and on
the
AASHTO web
http://ctpp.transportation.org/
On December 9, 2008, the Census Bureau plans to release the first
3-year
ACS products (surveys completed in 2005, 2006 and 2007). The minimum
population threshold is 20,000 for the 3-year products, compared to
65,000 population for the ACS 1-year products. So, while the data is
still "swiss cheese," that is, geographic coverage has holes, a lot
more geographic units will be available. The results are still
subject
to the Census Bureau rules of "collapsing and filtering" which means
that sometimes the data have been suppressed and you will see an "N".
We are now designing new profile sheets, in which we plan to include
data from 2000 (using Census Summary File 3 and CTPP2000) and from
2005-2007 ACS. Please let me know if you have any recommendations
for
specific tables to include (the data must be available in both 2000
and
from the 2005-2007 ACS). One recommendation from Nathan Erlbaum
(NYS
DOT) is to create a spreadsheet macro that will sum up multiple
geographic units and re-calculate the Margin of Error (using the
materials on Page 96-98 in NCHRP Report 588).
Also, I am wondering if there is any interest in an updated "Journey
to
Work Trends" report to include the 2005-2007 ACS results.
http://www.fhwa.dot.gov/ctpp/jtw/index.htm This report was limited to
metropolitan areas with population over 1 million, but had trend data
including 1960, 1980, 1990 and 2000. Because of redefinitions of
metropolitan areas by OMB, the data need to be accumulated from county
records for historical comparability, which makes for quite a bit of
work. The last report used the 1999 definition, but the 2005-2007
ACS
data will be reported using the 2007 OMB definitions (I think). My
question for you is: is this report useful enough to spend time and
resources on?
Thanks in advance for your opinions.
Elaine Murakami
FHWA Office of Planning (Wash DC)
206-220-4460 (in Seattle)
