I would also be interested in a more detailed explanation of why we should not compare overlapping period estimates. From a practical standpoint, people are going to do it anyway, especially the press. What
do we need to know – other than the inherent issues of what is a statistically significant vs. insignificant change and the fact that ACS was designed to examine characteristics of the population rather than its level – to be able to correct naïve interpretations
of easily calculated tract-level year-to-year differences in the estimates of things like poverty rate, unemployment rate, educational attainment rates, etc.? What is a correct interpretation of these differences?
Frank
Frank Lenk
Director of Research Services
Mid-America Regional Council
600 Broadway, Suite 200
Kansas City, MO 64105
816.474.4240
816.701.8237
From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net]
On Behalf Of Kendra Watkins
Sent: Monday, January 31, 2011 10:05 AM
To: ctpp-news@chrispy.net
Subject: RE: [CTPP] 2000 and 2006-08 work trip comparison question.
This is interesting. I recall hearing this guidance in the past. However on the Census website on the ACS page it specifically states; “Generally,
you can compare American Community Survey (ACS) 3-year and 5-year estimates with Census 2000 data. There are differences in the
universe, question wording, residence rules, reference periods, and
the way in which the data are tabulated which can impact comparability.”
The qualifier in the second sentence addresses the conflict (different methods, time periods etc) but I can’t find anywhere on the ACS pages where the Census recommends
we not compare ACS to decennial Census. And when I search by subject the Journey to Work topic states that I can ‘Compare’ it to the 2000 Census.
It does specifically state not to compare overlapping years on multiyear estimates.
Kendra Watkins
Senior Data Analyst
Mid-Region Council of Governments
809 Copper Ave. NW
Albuquerque, NM 87102
Phone: (505)724-3601
Fax: (505)247-1753
Email: kwatkins@mrcog-nm.gov
This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to which they are addressed. If you have received
this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.
From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net]
On Behalf Of Weinberger, Penelope
Sent: Monday, January 31, 2011 8:41 AM
To: ctpp-news@chrispy.net
Subject: RE: [CTPP] 2000 and 2006-08 work trip comparison question.
The CB does not recommend comparing an ACS based data set to a CB Long Form based data set. The 2000 data represent a point in time estimate, the ACS data represent a period estimate. Furthermore, the Census
Bureau recommends not comparing period estimates with overlapping years.
Penelope Weinberger
CTPP Program Manager
AASHTO
202-624-3556
http://ctpp.transportation.org/Pages/default.aspx
It's just as bad to not make a plan as to blindly follow the one you already have.
From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net]
On Behalf Of Seidensticker, Dan
Sent: Friday, January 28, 2011 4:18 PM
To: (ctpp-news@chrispy.net)
Subject: [CTPP] 2000 and 2006-08 work trip comparison question.
We downloaded the2006-2008 ACS county-to-county worker flow for Dane County, Wisconsin from
http://ctpp.transportation.org/Pages/3yrdas.aspx.
The question we now have…can that data be compared to the county-to-county 2000 CTPP work trips to determine any statistically significant increase/decrease? If so, how would one calculate the margin of error?
Dan Seidensticker
GIS Specialist
Madison Area Transportation Planning Board:
A Metropolitan Planning Organization (MPO)
City of Madison Planning Unit
121 S. Pinckney Street, Suite 400
Madison, WI 53703
Voice: 608-266-9119
Fax: 608-261-9967
Email:
dseidensticker@cityofmadison.com
www.MadisonAreaMPO.org