Confidentiality - Data Swapping

Research Project

chart from data swapping project

NISS studied how to conduct data swapping, one of a number of techniques meant to distort confidentiality-threatening high-dimensional characteristics of a database while preserving non-threatening low-dimensional characteristics. Data swapping exchanges attribute values between records. The issues to be studied are selection of the swapping rate, of attributes to be swapped and of candidate data records for swapping.

Later, NCES asked the National Institute of Statistical Sciences (NISS) to convene a technical panel of survey and policy experts to examine the NCES current and planned data dissemination strategies for confidential data with respect to: mandates and directives that NCES make data available; current and prospective technologies for protecting and accessing confidential data, as well as for breaking confidentiality; and the various user communities for NCES data and these communities’ uses of the data. The principle goals of the technical panel were to review the NCES current and planned data dissemination strategies for confidential data, assessing whether these strategies are appropriate in terms of both disclosure risk and data utility, and then to recommend to NCES any changes that the task force deems desirable or necessary. The NISS technical panel delivered its report to NCES in 2008. The report included four principal recommendations, the first three of which confirmed existing NCES strategies and practices:

  1. The technical panel recommended that all NCES analyses and publications be based on restricted databases produced by applying data swapping operations to original data as collected and edited.
  2. The technical panel also recommended that access to restricted databases be controlled under license from NCES.
  3. The panel recommended that NCES produce public databases whenever possible (by applying further appropriate statistical disclosure limitation techniques) and provide access to the public databases electronically by means of a data access system (DAS).
  4. Furthermore the panel recommended that NCES tailor the user interfaces of data access systems to user communities.

Technical Report(s):

Technical Report 126: NISS WebSwap: A Web Service for Data Swapping
Technical Report 131: Distortion Measures for Categorical Data Swapping
Technical Report 132: A Risk-Utility Framework for Categorical Data Swapping
Technical Report 134: Data Swapping: A Risk-Utility Framework and Web Service Implementation
Technical Report 140: Data Swapping as a Decision Problem

Software: NISS developed  NISS WebSwap, a web service that swaps one or more attributes (fields) between user-specified records in a microdata file, uploading the file containing the swapped records.

Project Goal: 

Find an effective way to protect confidentiality in a database while sharing enough information to make the database useful.

Research Team: 

Principal Investigator(s): Alan Karr, NISS

Senior Investigator(s): Ashish Sanil, Chunhua "Charlie" Liu

Post Doctoral Fellow(s):  Shanti Gomatam

Individual Team Members: 
Alan F. Karr