ctpp-news March 2009

ctpp-news@mailman.chrispy.net

57 participants
28 discussions

CTPP webinar on using IPUMS to analyze ACS PUMS

by Elaine.Murakami＠dot.gov

We are hosting a short session to train users on using the Minnesota Population Center IPUMS . http://usa.ipums.org/usa/ The IPUMS project provides a user-friendly approach to using decennial Census and ACS Public User Microdata Samples (PUMS) including the newest 2005-2007 ACS file and the Census 2000, and many older decennial census files. These microdata samples are a portion of the full individual records and include all the variables. The data are NOT pre-tabulated. If you need a quick tabulation that is not included in a CTPP or a standard Census file like Summary File 3, or the American FactFinder, then using the microdata may be a solution for you. The PUMS are restricted to larger geographic units (Public Use Microdata Area) to protect individual confidentiality. For example, Nathan Erlbaum from New York State recently wanted to know the the impact of group quarters population on bicycle commuting. I ran a table using Census 2000 (includes group quarters) and 2005 ACS (excludes group quarters). Probably I should have compared 2005 ACS to 2006 ACS! By the way, the answer was that group quarters had a large effect on walking for the mode to work, and not much difference on bicycling. You do not need to have statistical software installed on your PC. The SDA program in IPUMS can run simple tabulations, regressions, and logit models. We will learn basic techniques to select rows and columns, filtering (subsetting), re-grouping variable classifications (very important for continuous variables like travel time, departure time, age, income) and even try a simple regression. The on-line software cannot do as sophisticated variable processing as a system like SAS or S+, but it can provide analysts with a quick way to examine basic patterns that can be used to design more sophisticated analyses. DATE: April 16, 2009 Thursday TIME: 1 - 2:30 p.m. Eastern Pre-registration is required: http://www.nhi.fhwa.dot.gov/resources/webconference/web_conf_learner_reg.as… I have reserved 65 slots. Hope to see you there! IPUMS for Census Data Main instructor: Katie Genadek, Minnesota Population Center, IPUMS project. Elaine Murakami FHWA Office of Planning 206-220-4460 (in Seattle)

15 years, 9 months

Alison K Fields/POP/HQ/BOC is out of the office.

by alison.k.fields＠census.gov

I will be out of the office starting 03/17/2009 and will not return until 03/23/2009. If you need immediate assistance please see one of the people acting for me during my absence. Kin Koerber - March 17- March 19 Melissa Chiu - March 20 For all CTPP-related matters please see Melissa Chiu.

15 years, 9 months

John C Joiner/COA is out of the office.

by John C Joiner

I will be out of the office starting 03/10/2009 and will not return until 03/19/2009.

15 years, 9 months

ACS 5-year Federal Register Notice

by Ed Christopher

I am not sure if others are pondering what the recent Federal Register notice on ACS 5-year data products really means but I believe that there are some “key” facts missing. Facts that would allow users’ the ability to asses the true impact of the rules. For example: Rule 7 of the Disclosure Avoidance rules states that “For the residence and workplace tables where means of transportation (mode) is crossed with one or more other variables, there must be at least three unweighted workers in sample for each transportation mode in a given place for the table to be released. Otherwise the data must be collapsed or suppressed and complementary suppression must be applied. There is no threshold on univariate tables.” http://www.census.gov/acs/www/Downloads/proposal_acs5yearproducts.pdf While this might sound very straight forward we know from the “statistical collapsing” rules that were applied to the 3-year data that only one collapsing attempt is made of the data and if the table does not pass it is tossed out (suppressed). What we do not know about the current rule is what will the collapsing hierarchy be, and will the Census continue collapsing modes into each other until the threshold is met? Both the Federal Register notice and the rules are silent on this issue. In some recent work done for FHWA by the Census Bureau we do know that at a Tract level a great deal of data will be suppressed under Rule 7. Using 5-year data from five of the ACS test counties, Multnomah, Lake, Broward, San Francisco and Bronx we do know that if all 17 modes (means of transportation) are used only 3 to 8 percent of the Tracts would have enough data to be released. However, if we cut the number of modes down to only 4 including Drove Alone, Carpooled, Transit, and other including work at home somewhere between 5 and 37 percent of the tables will be suppressed. And that is at the TRACT level! If per chance someone wants to go one step up the modal ladder and split out “bike and walk” and make work at home a separate category yielding 6 modal categories, upwards of 80 percent of the TRACT level tables can expected to be suppressed. At the Block Group the suppression will be only worse. -- Ed Christopher Resource Center Planning Team Federal Highway Administration 19900 Governors Drive Olympia Fields, Illinois 60461 708-283-3534 (V) 708-574-8131 (cell) 708-283-3501 (F)

15 years, 9 months

CB Federal Register Notice: ACS 5-year data products proposal

by Murakami, Elaine

Dear Everyone: Today, the Census Bureau issued this Federal Register notice. The 5-year ACS is the first ACS product for small area geography, e.g. census tracts and block groups. I have extracted KEY POINTS that will GREATLY IMPACT data availability for transportation tables and result in a lot of DATA SUPPRESSION at the tract and block group level. As this FR was just issued today, we have not had a chance to estimate the amount of suppression that would occur given these proposed conditions. We are currently working on profile sheets using the 2005-2007 ACS (3-year data) that was released in December 2008. We are finding many tables to be suppressed. So, even with the population threshold of 20,000 for the 3-year ACS data, there is considerable suppression on the current ACS standard table production, at least those tables of key interest to transportation planners. As most of you know, the first CTPP using ACS is a planned 3-year accumulation from ACS 2006-2008. The table list will be re-submitted by AASHTO to the Census Bureau in a few weeks. The next CTPP product is envisioned as a 5-year accumulation from ACS 2006-2010. Because of the many rules the CB has established to protect individual confidentiality not just for the ACS Standard tables, but also for custom tabulations like the CTPP, we believe that the 5-year CTPP for small area tabulation (e.g. TAZs) will need to rely on synthetic data generated inside the CB using the ACS microdata records. _________________________________________________________ *Federal Register Notice: The 5-Year ACS Data Products Release Plan Today the U.S Census Bureau published its data release plan for the ACS 5-year data products in the Federal Register (E9-4803). Beginning in late 2010, the Census Bureau plans to introduce 5-year data products covering the January 2005 through December 2009 data collection period. The release of the 5-year estimates will achieve the goal of the ACS to provide small area data similar to the long-form sample data published after Census 2000. The Census Bureau is proposing to modify its current line of data products to accommodate the 5-year estimates and is requesting comments from current and potential users of ACS data products to help guide this modification. We invite you to review the 5-Year ACS Data Release Plan and provide your response to the contact listed in the Federal Register notice. Please follow this link to the Federal Register notice (PDF files) posted in the Highlights section on the ACS Main page: http://www.census.gov/acs/www/ Comments are due to the contact listed in the Federal Register notice by April 20, 2009 >From the Census Bureau's pdf document: 2. Detailed tables with more than 100 cells cannot be released at the block group level. 5. For the Selected Population Profiles, there must be at least 50 unweighted sample cases over the 5-year period in the universe (specific population subgroup) in a given geographic area for the profile to be released. 6. For workplace tables, there must be at least 50 unweighted or 300 weighted workers in sample over the 5-year period in a given workplace for the table to be released. 7. For the residence and workplace tables where means of transportation (mode) is crossed with one or more other variables, there must be at least three unweighted workers in sample for each transportation mode in a given place for the table to be released. Otherwise the data must be collapsed or suppressed and complementary suppression must be applied. There is no threshold on univariate tables. Elaine Murakami FHWA Office of Planning elaine.murakami(a)dot.gov Note: please update my contact information. My previous email address will likely expire on March 11. 206-220-4460

15 years, 9 months

John C Joiner/COA is out of the office.

by John C Joiner

I will be out of the office starting 03/05/2009 and will not return until 03/09/2009.

15 years, 9 months

Re: [CTPP] CB Federal Register Notice: ACS 5-year data products proposal (Out of Office Reply)

by Nathan Erlbaum

I am out of the office from Mon 3/2 - Fri 3/6 , returning possibly 3/9 weather permitting. If you have an IT issue, please carbon Bob Curtis as he will proxy for me in my absence. If you have a GIS issue please contact Aaron Westcott, I will have limited e-mail access but will be monitoring my messages. If it is a technical question I'll get back to you upon my return.

15 years, 9 months

Diana Portillo is out of the office.

by Diana Portillo

I will be out of the office starting 03/05/2009 and will not return until 03/11/2009.

15 years, 9 months

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ctpp-news March 2009