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)
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