14 Dec
2010
14 Dec
'10
7:36 p.m.
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_metho…
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<mailto:todd.graham@metc.state.mn.us>
in: www.linkedin.com/in/toddgraham
web: http://stats.metc.state.mn.us/
________________________
From: ctpp-news-bounces(a)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(a)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(a)nashvillempo.org
http://www.nashvillempo.org<http://www.nashvillempo.org/>
From: ctpp-news-bounces(a)chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of
Elaine.Murakami(a)dot.gov
Sent: Tuesday, December 07, 2010 4:15 PM
To: ctpp-news(a)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(a)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(a)census.gov