Census Data Stewardship Executive Policy Committee Meeting

Meeting Summary

Census Data Stewardship Executive Policy Committee Meeting

August 28, 2008

Regarding: AASHTO Appeal of Census Bureau Disclosure Review Board Rules

for the American Community Survey 3-Year Data Tabulations

Presenter’s Representing AASHTO

-Jack Basso, AASHTO

-Gloria Shepherd, Federal Highway Administration (FHWA)

-Alan Pisarski, Consultant and Member of the AASHTO CTPP Oversight Board

-Tom Krenzke, Westat

Other Meeting Participants:

-Census Bureau Data Stewardship Executive Policy (DSEP) Committee Members

-Census Bureau staff

-Ron McCready, AASHTO

-Elaine Murakami, FHWA

-Ed Christopher, FHWA

-Mark Freedman, Westat

Background

In February 2008, AASHTO submitted a list of priorities for 3-year ACS special data tabulations. Following this submittal, AASHTO was notified by the Census Bureau that new Disclosure Review Board (DRB) rules have been established for the 3-year ACS tables that requireindividual “cells” to have at least 3 unweighted records to avoid suppression.

The level of suppression required under the new Census Bureau disclosure rules significantly diminish the utility of the 3-year ACS data for the transportation community, especially in regards to understanding trends related to means of transportation to work.
AASHTO’s position has been that ACS survey design sufficiently minimizes disclosure risks and obviates the need for further data suppression. AASHTO has asked the Census Bureau to work with the transportation community to strike a balance that can preserve data utility.
AASHTO presented it position to the Census Bureau DRB. The DRB declined to change the rules. AASHTO asked for an appeal and this meeting was scheduled with the Census Bureau Data Stewardship Executive Policy (DSEP) Committee.

Meeting DiscussionHighlights

Jack Basso, AASHTO, spoke first on the importance of the data, the financial role of the states and the AASHTO role in the CTPP program.

Gloria Shepherd, FHWA, echoed the importance of the CTPP data to the transportation community in fulfilling statutory requirements. Ms. Shepherd noted that the Census Bureau and transportation community need to work together. Withholding data is not a good solution.

Alan Pisarski gave a presentation summarizing issues and concerns with the Disclosure Review Board requirements and reasons why AASHTO believes the disclosure rules are not needed.

Tom Kenske shared the results of a statistical analysis Westat did for AASHTO. The results indicate that the risks of creating a pseudo micro data record from CTPP data were low (0.5% - 3%).

Laura Zayatz, Chair of the Census Bureau Disclosure Review Board, addressed AASHTO concerns. She stated that the population threshold for releasing microdata records was typically 100,000 and sometimes 250,000. Laura indicated that DRB believes the CTPP tabulations could be used to create microdata records. The new disclosure rules are needed to prevent this from happening.
The AASHTO appeal listed a number of standard techniques, such as swapping, that AASHTO believes protect confidentiality. Ms. Zayatz explained that data swapping did not help protect a record because the swapping generally occurs within the same geographic tabulation unit for the 3-year data (e.g. the state county or same city).
Ms. Zayatz additionally discussed the record re-identification work that the Census Bureau did in 2002. As part of this work, Census Bureau staff took a microdata record, matched it to PUMS and then by using files available on the Internet they were able to correctly identify a specific individual by name.

During the meeting, there was a discussion about allowable risk of disclosure. There seemed to be agreement among Census Bureau DSEP Committee members that the Westat estimate of 0.5% - 3% was too high and that they were inclined to not accept any risk in respect to disclosure.

Mr. Pisarski noted that the current AASHTO data request was no more demanding than past tabulation requests. In fact, the current AASHTO request has fewer collapsed variables than past CTPPs that were approved for release. Census Bureau DSEP members responded that new internet capabilities and advanced search engines are changing the environment in which the Census Bureau works and that they need to be increasingly stringent to preserve disclosure security.

Toward the end of the meeting, Nancy Gordon, Census Bureau, advised AASHTO and US DOT to work together on data synthesis methods, especially on opportunities for combining ACS and the new Longitudinal Employer Household Dynamics (LEHD) data. Ms. Gordon suggested that this would take significant resources, well beyond the small $50,000 contract that NCHRP currently has underway on this subject.

Bob Kominsky, Census Bureau, recommended that the transportation community rely less on special data tabulations and focus more on the use of ACS standard tables.

Ms. Shepherd asked about next steps. Tom Messenbourg, Census Bureau, said that the Census Bureau had already scheduled a follow up meeting and that a decision should be transmitted to AASHTO by mid-September. Mr. Messenbourg, did note that DRB rulings have not been over-turned in the past.

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