Frank:
 
I agree wholeheartedly with your concerns.  One particular issue that we, as data 'superusers' need to remember, is every federal, state, and nonprofit application for aid, grants, loans, etc. will still ask for the same information for a set time.  The vast majority of people are still--and will be for a long time--used to using data derived from a "point in time snapshot".  Getting us used to working with 'trends' and 'characteristics' has been difficult enough.  We now have to pass that knowledge and practice onto those to whom we give that data, whether it be the press, elected officials, nonprofit agencies, students, or the general public.
 
This goes beyond our transportation uses, but at the same time has a significant impact on our transportation uses of these data.
 
Michael D. Golembiewski
Transportation Modeler
 
BERKS COUNTY PLANNING COMMISSION
633 Court Street FL 14
Reading, PA 19601
Ph: 610 478-6300 ext 6304
Fax: 610 478-6316
e-mail: mgolembiewski@countyofberks.com
Web:  http://www.co.berks.pa.us/dept/planning
 
Note: The comments on and attachment to this e-mail are intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law.  If the reader of this message is not the intended recipient, your are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you received this in error, please contact the sender and delete the original message, any attachment(s) and copies.  Thank you for your cooperation.
 

From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Frank Lenk
Sent: Tuesday, February 01, 2011 2:30 PM
To: ctpp-news@chrispy.net
Subject: RE: [CTPP] 2000 and 2006-08 work trip comparison question.

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

www.marc.org

816.474.4240

flenk@marc.org

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