I agree with Patty Becker that the Block Group-level stats are
shaky. I'd posted on this question to the Census SDC listserv a few months
back. I'll share it here (CTPP list) as well...
According to Chapter 3 of the Bureau's ACS Design and Methodology,
the "frame" for ACS 2005-09 is still the Census 2000 MAF with five
kinds of POST-2000 maintenance. (So the frame for the ACS data released this
Fall is not the 2010 MAF.)
If I understand Chapter 11, Census has taken some steps as Census
Tract-level quality control. Still Tract totals are simply the Tract-level
frame counts from the MAF, validated with administrative data counts. See http://www.census.gov/acs/www/Downloads/survey_methodology/acs_design_methodology_ch11.pdf
for details (starting on page 11.17)
As for Block Groups... ACS housing unit totals, pop totals, and
other data for Block Groups are simply BG-level sums of weights of cases that
happen to be geolocated within the BG. Beyond that, Block Groups are
unaddressed in the control total and weighting methodology. So there’s great
potential, from a research design standpoint, for screwy results at BG-level.
Bottom line: Yes, the BG-level numbers you see in ACS 2005-09 are
very shaky. And the ACS 2006-10 data that will be released 12 months from now
-- with all the raw survey-collected data re-weighted -- could look very
different at Block Group level.
________________________
Todd Graham
Principal Forecaster
Metropolitan Council
390 Robert Street North
Saint Paul, MN 55101
ph: 651/602-1322
email: todd.graham@metc.state.mn.us
in: www.linkedin.com/in/toddgraham
web: http://stats.metc.state.mn.us/
________________________
From:
ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On
Behalf Of Lindeman, Nicholas (MPO)
Sent: Tuesday, December 14, 2010 10:42 AM
To: ctpp-news@chrispy.net
Subject: RE: [CTPP] ACS 2005-09 comparisons with 2000 SF3
Does anyone know why the Block Group data is not being released
via the AFF’s standard pull-down menus? I was under the impression that today (12/14)
was the release date for this data. I understand that it is available via
Summary File, but this is far from user friendly.
When will the data be available via the AFF’s standard access
method?
Thank you,
Nick Lindeman
Nicholas Lindeman
Economic & Systems Data Analyst
Nashville Area MPO
800 2nd Ave. S.
P.O. Box 196300
Nashville, TN 37219-6300
(615) 862-7198
lindeman@nashvillempo.org
http://www.nashvillempo.org
From:
ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On
Behalf Of Elaine.Murakami@dot.gov
Sent: Tuesday, December 07, 2010 4:15 PM
To: ctpp-news@chrispy.net
Subject: FW: [CTPP] ACS 2005-09 comparisons with 2000 SF3
Correction to my earlier email: 2005-2009 ACS Block Group
data WILL be released on December 14.
From: brian.mckenzie@census.gov
[mailto:brian.mckenzie@census.gov]
Good Afternoon
Mara and Elaine,
The summary
file data (block group level data) will be available on December 14th. You can
use American Factfinder as a portal. You will be able to download summary file
data via the FTP website at <http://www2.census.gov/acs2009_5yr/summaryfile/>. There will also
be a clickable link next to the familiar portion of AFF in which you select the
desired ACS year(s) for which you would like data. Hope this helps.
Brian McKenzie
Analyst, Journey to Work and Migration Statistics Branch
U.S. Census Bureau
301-763-6532
brian.mckenzie@census.gov