Bureau of the Census, Department of Commerce.
The Bureau of the Census (Census Bureau) is issuing this Notice to update the criteria used to assess and review public use data products prior to their release. The criteria help ensure that confidential information is not inadvertently disclosed.
This notice is effective May 5, 2003.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Requests for additional information on this Notice should be directed to Laura Zayatz, Chair, Disclosure Review Board, Statistical Research Division, U.S. Census Bureau, Room 3209, Federal Building 4, Washington, DC 20233, (301) 763-4955 or by fax at (301) 457-2299.End Further Info End Preamble Start Supplemental Information
Title 13, United States Code, Section 9, requires the Census Bureau to protect the confidentiality of individual respondents. Title 13 also requires the Census Bureau to release information from its data collections to the public. In order to comply with the latter requirement, while protecting respondents' confidentiality, the Census Bureau has developed standard procedures for protecting its data products from disclosure of identifying information. A Federal Register Notice (46 FR 22017) published on April 15, 1981, described those procedures.
Since that Notice appeared, some methodological improvements have been introduced and additional formal review has been instituted. Specific changes to the earlier criteria are the following items under the “Criteria for Releasing Public Use Microdata” section of this Notice.
- Paragraph (4). To ensure confidentiality protection, the Census Bureau now requires the completion of a Checklist on Disclosure Potential of Data.
- Paragraph (4)(e). To better protect the confidentiality of data, the Census Bureau may require the use of data swapping. This technique is discussed further in that paragraph.
- Paragraph (5). The name of the Microdata Review Panel was changed to the Disclosure Review Board.
- “Criteria for Releasing Public Use Tabular Data” section. This entire section is new. In 1995, the routine review performed by the Disclosure Review Board was extended to include tabular data as well as microdata.
Also, the scope of the Disclosure Review Board was enlarged to include setting disclosure limitation rules, monitoring the Census Bureau's adherence to its confidentiality policy requirements, and resolving any problems, questions, and issues not covered by the general criteria described in the earlier Federal Register Notice. This Notice updates the information previously published and includes criteria for releasing tabular data as well as microdata.
Confidentiality Criteria for Census Bureau Public Use Data Products
Data Subject to Disclosure Protection
All data released to the public are subject to disclosure protection. These public use data products include both microdata and tabular data. Microdata Start Printed Page 23694are records containing information about individuals or households, or about businesses, with all personal identifiers removed. Tabular data may be frequency counts (e.g., number of Hispanic males) or magnitude data presenting sums of a variable of interest (e.g., total value of sales) from individuals, households, firms, or establishments.
Because some business firms and establishments are selected with certainty, the disclosure risk for economic microdata files can be quite high. For this reason, microdata files containing information on establishments are rarely produced. However, any economic microdata file produced for public release would be subject to disclosure constraints comparable to those provided for individual and household microdata files.
Criteria for avoiding disclosure in data released by the Census Bureau for public use have been the subject of internal research, consultations with stakeholders, and input from experts in disclosure limitation techniques over the past few decades. Based on those findings and subsequent assessments of data needs and disclosure risk, the Census Bureau has established a release policy stating criteria for release. The Census Bureau will apply these criteria to all data products released to the public.
Criteria for Releasing Public Use Microdata
Files of records containing data about households and individuals, or about businesses, can be made available for public use, provided the appropriate disclosure avoidance requirements have been met. For public use microdata about individuals and households, the following conditions must be met:
(1) The records contain no names, addresses, or other unique identifiers.
(2) The records include no geographic or related information that would identify an area of fewer than 100,000 population.
(3) Once a file has been released with one set of geographic identification, the same records cannot be released with different identification if the two geographic schemes in combination identify any area with fewer than 100,000 population.
(4) Specifications for each file (or groups of files) must be reviewed to assure that confidentiality is protected. To do so, the Census Bureau's Checklist on Disclosure Potential of Data must be completed by the data producers and reviewed by disclosure experts at the Census Bureau. (The Checklist is available on the Census Bureau Web site at http://www.census.gov/srd/sdc/index.html.) This review may result in:
(a) The removal or reduction in detail of any variable considered likely to identify an especially small and visible population (e.g., persons with high income or rare demographic characteristics).
(b) The use of a minimum area population criterion that is higher than 100,000 for that particular file(s) (e.g., for a file with neighborhood characteristics).
(c) The introduction of “noise” (i.e., small amounts of random variation) into selected data items.
(d) The subsampling of records so that public-use microdata do not include all respondents included in a large survey.
(e) The use of data swapping (i.e., locating pairs of matching households in the database, based on a set of predetermined variables, and swapping those households across geographic areas to add uncertainty for households with unique characteristics).
More information on these methods is provided on the Census Bureau's Internet site at http://factfinder.census.gov/home/en/confidentiality.html#microdata.
(5) The Disclosure Review Board concurs that the data meet disclosure avoidance criteria for public release.
Comparable criteria will be developed and applied in the event that microdata about businesses are being considered for public release.
Criteria for Releasing Public Use Tabular Data
Although tabular data products had routinely undergone disclosure protection, it was not centralized. This Notice documents standardized procedures now in use that have been adopted to protect the confidentiality of information in frequency counts and magnitude data. Tabulations containing data about households, individuals, firms, and establishments can be made available for public use provided that:
(1) Specifications for each file (or groups of files) are reviewed to assure that confidentiality is protected for any response provided by an individual, a household, a firm, or an establishment. To do so, the Census Bureau's Checklist on Disclosure Potential of Data is completed by the data producers and reviewed by disclosure experts at the Census Bureau. (The Checklist is available on the Census Bureau Web site at http://www.census.gov/srd/sdc/index.html.) This review may result in:
(a) The removal or reduction in detail of any variable in a tabulation considered likely to identify an especially small and visible population or group of establishments.
(b) The introduction of “noise” into selected data items.
(c) The use of data swapping for selected households.
(d) The use of rounding in selected tabulations.
(e) The use of thresholds in selected tabulations.
(f) The use of cell suppression (i.e., not displaying certain cell values that would identify unique cases in a table or disclose an individual response; often complementary cells also are blanked out to prevent disclosures by subtracting the balance from the total for a given row or column).
(2) The Disclosure Review Board concurs that the data meet disclosure avoidance criteria for public release.Start Signature
Dated: April 29, 2003.
Charles Louis Kincannon,
Director, Bureau of the Census.
[FR Doc. 03-10952 Filed 5-2-03; 8:45 am]
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