17. Appendix E: More About Statistical Masking Methods

There are a number of alternative methods that are available for statistical masking. Use of any alternative method for de-identification must be reviewed and approved by the PRT.

Methods discussed in the Federal Committee of Statistical Methodology’s “Statistical Policy Working Paper 22 (Second version, 2005), Report on Statistical Disclosure Limitation Methodology” include the following for tables of counts or frequencies and for magnitude data. Additional information is available through the committee’s Data Protection Toolkit.

• Tables of Counts or Frequencies

  • Sampling as a Statistical Disclosure Limitation Method

  • Defining Sensitive Cells

    • Special Rules

    • The Threshold Rule

  • Protecting Sensitive Cells After Tabulation

    • Suppression

    • Random Rounding

    • Controlled Rounding

    • Controlled Tabular Adjustment

  • Protecting Sensitive Cells Before Tabulation

• Tables of Magnitude Data

  • Defining Sensitive Cells – Linear Sensitivity Rules

  • Protecting Sensitive Cells After Tabulation

  • Protecting Sensitive Cells Before Tabulation