I would like to make a special request to the consulting community to please WEIGH IN. Often you are the ones who are building models for more than one MPO, County, or other transportation agency. PLEASE TAKE THE TIME to review the list and provide your input. If there is a table that you have often used at small geographic scale and it is marked in BLUE (possible deletion), please make sure that Penelope Weinberger (pweinberger@aashto.org) gets your input so that the table will be retained. Of course, you can’t predict with 100% confidence the tables you will need in the future (even if you are forecasters), but I think that you might find that a small subset e.g. 5 – 12 tables is highly useful and so you tend to use the same ones in different locations, for different projects.

Today Stacey Bricka reported “significant” differences in a tabulation using the American FactFinder and ACS PUMS. Since the PUMS is only a SAMPLE of the ACS sample, it is always better to use the American FactFinder if it includes the specific table you want. In addition, the CB adds more noise and uses “top coding” in the PUMS to reduce the possibility of disclosing individuals. Stacey is going to pull documentation together so that we (and/or the CB) can research the problem.

So, it is better to include the tables in the CTPP list than to say that you will IPF (Fratar) the table using large geography (e.g. PUMA) and PUMS, with one-way distributions from CTPP for small geography.

Elaine

From: ctpp-news-bounces@chrispy.net [mailto:ctpp-news-bounces@chrispy.net] On Behalf Of Weinberger, Penelope
Sent: Monday, April 26, 2010 1:09 PM
To: ctpp-news@chrispy.net
Subject: RE: A correction. [CTPP] Help determine our request to US CensusBureau for CTPPSpecial Tabulations based on ACS 5-year(2006-2010) Data
Importance: High

Please disregard the original email and go with this one instead, the chief difference being that there is no “three unweighted records for Means of Transportation (MOT) rule” since we have only five variables we are crossing with MOT.

Penelope Weinberger

CTPP Program Manager

AASHTO

202-624-3556

http://ctpp.transportation.org/home/default.htm

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 Weinberger, Penelope
Sent: Monday, April 26, 2010 3:45 PM
To: ctpp-news@chrispy.net
Subject: [CTPP] Help determine our request to US Census Bureau for CTPPSpecial Tabulations based on ACS 5-year (2006-2010) Data

Dear CTPP Community,

This is an opportunity for your input on the upcoming CTPP based on 5-year ACS 2006-2010!

This message contains colored highlighting, if you cannot see it, please view the message in HTML (if possible).

Please download the attached spreadsheet, mark it as appropriate according to the instructions and information below, and return it attached to an email directly to me by Friday, May 7^th, 2010 pweinberger@aashto.org (Please do not reply to the whole list with your marked attached spreadsheet, for that will create a version control nightmare!)

The attached spreadsheet is a proposed table list to submit to the Census Bureau for special tabulations based on the 5-year ACS, it is derived from the Census Bureau’s Disclosure Review Board’s approved CTPP from 3-year ACS data table list.

For large area geography, we plan to keep the table list the same as the current 3-year table list (the spreadsheet, as if there were no highlighting).

For small area geography (tract, TAZ, and block group), we are proposing to eliminate many of the tables with 3-way cross-tabulations, or 2-way cross-tabulations with more than 40 cells because we suspect they will contain very little or no data. We have highlighted the tables proposed for deletion at small geography in BLUE. Please identify any highlighted tables you feel are important to keep, and not be eliminated by placing a mark in the specified column and row.

Alternatively, if you see tables that are not marked for deletion at small geography please feel free to let me know there is no need for those tables, it would be a waste of resources to generate data that is essentially useless to the transportation planning community.

The number of classifications in each variable may need to be reduced to pass the CB’s criteria and some of those tables have been highlighted in pink, we are including this information to start thinking about the ways variable groups can collapse.

For the ACS 2006-2010 five-year data and the 2010 Census Tracts, there is projected to be, on average, a little over 4000 residents per tract, and approximately 120 household records and 150 worker records in the unweighted sample.

There are general special tab rules that apply to all tabs, which are not CTPP specific. For instance, all aggregates and averages require 3 unweighted cases in the CELL. The 5-year data has no lower bound for place size. There is no rule yet in place for maximum number of cells per table, a number has been discussed, but not decided upon.