Hey Ken:
The ultra-long distance commuters I just throw away. I put them in the
same bucket as the weekly absentees. Or, it may help to try to sort the
commute data into: commutes from home-to-work; and, commutes from "not
home"-to-work. (Note that the census doesn't ask where you started your
commute, it asks: "at what location did this person work last week?"
Though the question on commute time departure *does* ask: "What time did
this person usually leave home to go to work last week?")
For interregional commuters, I use my common sense and select the
counties neighboring my region that have legitimate opportunities for
daily commute trips. Perhaps this is a three-hour maximum from the edge
of the region?
Counties in California are fairly large, so I use just 12 neighbor
counties surrounding the SF Bay Area. Texas has MANY smaller-sized
counties, so I imagine you would have an inner ring and outer ring(s) of
surrounding / neighboring counties. Then, if you have time, you can
build some tract-to-tract desire lines (with distance) to calculate the
tract-to-tract distances, reported average commute duration, and derived
commute speed, to determine if the interregional commutes are sensible
or silly. I don't know what I would do with a seemingly reasonable
interregional commute value that has a unreasonable travel time - -
perhaps the travel time is mis-coded, or perhaps this is another case
where the worker is NOT starting their commute from THEIR home!? I would
probably accept the numbers of commuters value, but blank out the
commute time as a missing value.
Another idea is to use the statewide travel model system to build a
statewide zone-to-zone commuter matrix, then develop commute length
(distance) frequency distributions to isolate the ultra-long,
intra-state commutes, their reported commute durations, and the derived
commute speeds. That would be preferable to a crow-flow distance desire
line analysis.
(By the way, I haven't tested any of these methods. They're just some
ideas to share.)
Chuck Purvis, MTC
>>> Ken Cervenka <kcervenka(a)nctcog.org> 05/18/04 03:56PM >>>
This question has probably been asked before, but I don't recall the
answer...
What sort of adjustments do people make with CTPP data, to deal with
the
extreme "long-distance" commuters that are actually just "temporarily
re-assigned" workers? This is not an error in the CTPP collection or
summary process, but rather a result of the way the long form questions
were
answered.
For example, here is a record that got "expanded" to four people:
-- The Place of Residence is a County in Alaska
-- The Place of Work is a County in Texas (Dallas)
-- The commute time is 20 minutes
What this is saying is that the person isn't really commuting each day
from
their home in Alaska, but is instead commuting to a place in Dallas
County
from some temporary residence (a hotel, perhaps) within the
Dallas-Fort
Worth area.
Such an extreme example is easy to recognize, but what about other
examples
which fall into the "not sure" category when it comes to whether a
person's
normal place of residence is really the point where they are truly
starting
their commute trip? Perhaps a very high "average speed" based on
"travel
time" and "straight-line distance" could be used to flag such records?
Ken Cervenka
North Central Texas COG
This question has probably been asked before, but I don't recall the
answer...
What sort of adjustments do people make with CTPP data, to deal with the
extreme "long-distance" commuters that are actually just "temporarily
re-assigned" workers? This is not an error in the CTPP collection or
summary process, but rather a result of the way the long form questions were
answered.
For example, here is a record that got "expanded" to four people:
-- The Place of Residence is a County in Alaska
-- The Place of Work is a County in Texas (Dallas)
-- The commute time is 20 minutes
What this is saying is that the person isn't really commuting each day from
their home in Alaska, but is instead commuting to a place in Dallas County
from some temporary residence (a hotel, perhaps) within the Dallas-Fort
Worth area.
Such an extreme example is easy to recognize, but what about other examples
which fall into the "not sure" category when it comes to whether a person's
normal place of residence is really the point where they are truly starting
their commute trip? Perhaps a very high "average speed" based on "travel
time" and "straight-line distance" could be used to flag such records?
Ken Cervenka
North Central Texas COG
-----Original Message-----
From: Pheny Smith [mailto:pheny.smith(a)bts.gov]
Sent: Thursday, May 06, 2004 11:04 AM
To: ctpp-news(a)chrispy.net
Cc: Jeff Butler; Deepak Virmani; Cheryl Young
Subject: [CTPP] Release of CTPP Part 3 Flat ASCII files
** High Priority **
Dear CTPP Users,
Thanks to the BTS Transtats team's effort, the preliminary CTPP 2000 Part 3
files are now available for download via the BTS Transtats Website. These
files are in Flat ASCII File format.
The website is: www.bts.gov, Click on Data, then on CTPP 2000.
For questions on the Flat ASCII files, please contact Nanda Srinivasan
(Nanda.srinivasan(a)fhwa.dot.gov) or Clara Reschovsky
(Clara.a.reschovsky(a)census.gov).
For problems on downloading files, please contact Deepak Virmani
(Deepak.virmani(a)bts.gov).
Pheny Smith, Ph. D.
Statistician
Office of Advanced Studies
Bureau of Transportation Statistics
(202) 366-2817
Today the Census Bureau published notice in the Federal Register that it
is requesting public comments on the current and proposed new ACS data
products. This should be especially important to the transportation
planning community especially with the prospect of annual data and that
at this time, there is no guarantee of a future CTPP like product.
Comments to the Docket need to be submitted by July 14, 2004. For a
copy of the text of the Federal Register notice go to
http://www.census.gov/acs/www/product_review/acs_survey/fed_reg.htm
To help users with their review, the Census Bureau has set up a "Current
and Proposed Products Review" website at
http://www.census.gov/acs/www/product_review/
More information about this notice can be found in the ACS Special Alert
at http://www.census.gov/acs/www/Special/Alerts/Latest.htm
--
Ed Christopher
708-283-3534 (V)
708-574-8131 (cell)
FHWA RC-TST-PLN
19900 Governors Dr
Olympia Fields, IL 60461
Andrew:
A year or so ago someone on this list provided a link to a site by the
Bureau of Economic Analysis. It has county-to-county total worker data
for 1970 through 1990:
http://www.bea.doc.gov/bea/regional/reis/jtw/
I checked it and it still works. They apparently haven't yet updated it
to include the Census 2000 data that was released over a year ago....
CP
>>> "Andrew PICKARD" <APICKARD(a)hrpdc.org> 05/06/04 02:20PM >>>
I am looking to find 1980 Census flow data at the county-to-county
level. There seem to be a handful of web sights with historical
Census
data but none with data from Census' recent past. Any help is
appreciated. Thanks!
Andrew Pickard, P.E.
Senior Transportation Engineer
Hampton Roads Planning District Commission
723 Woodlake Drive
Chesapeake, VA 23320
Phone: (757) 420-8300 Fax: (757) 523-4881
E-mail: apickard(a)hrpdc.org
Web: www.hrpdc.org
-------------------------------------------------------
I am looking to find 1980 Census flow data at the county-to-county
level. There seem to be a handful of web sights with historical Census
data but none with data from Census' recent past. Any help is
appreciated. Thanks!
Andrew Pickard, P.E.
Senior Transportation Engineer
Hampton Roads Planning District Commission
723 Woodlake Drive
Chesapeake, VA 23320
Phone: (757) 420-8300 Fax: (757) 523-4881
E-mail: apickard(a)hrpdc.org
Web: www.hrpdc.org
-------------------------------------------------------
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-----------------------------------------------------
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<<<<GWAVA has you covered>>>>
** High Priority **
Dear CTPP Users,
Thanks to the BTS Transtats team's effort, the preliminary CTPP 2000 Part 3 files are now available for download via the BTS Transtats Website. These files are in Flat ASCII File format.
The website is: www.bts.gov, Click on Data, then on CTPP 2000.
For questions on the Flat ASCII files, please contact Nanda Srinivasan (Nanda.srinivasan(a)fhwa.dot.gov) or Clara Reschovsky (Clara.a.reschovsky(a)census.gov).
For problems on downloading files, please contact Deepak Virmani (Deepak.virmani(a)bts.gov).
Pheny Smith, Ph. D.
Statistician
Office of Advanced Studies
Bureau of Transportation Statistics
(202) 366-2817
