NumSingleton: Decoding of 'singletonMethod'

In SSBtools: Statistics Norway's Miscellaneous Tools

Decoding of singletonMethod

Description

A GaussSuppression singletonMethod starting with "num" is decoded into separate characters. Part of the theory for interpreting the 3rd, 4th, and 5th characters is discussed in Langsrud (2024). To utilize possibly duplicated contributor IDs, the 2nd character must be "T".

Usage

NumSingleton(singletonMethod)

Arguments

singletonMethod

String to be decoded. If necessary, the input string is extended with F's.

Details

Any F means the feature is turned off. Other characters have the following meaning:

1. singleton2Primary (1st character):

   • T: All singletons are forced to be primary suppressed.

   • t: Non-published singletons are primary suppressed.

2. integerUnique (2nd character):

   • T: Integer values representing the unique contributors are utilized. Error if singleton not supplied as integer.

   • t: As T above, but instead of error, the feature is turned off (as F) if singleton is not supplied as integer.

3. sum2 (3rd character):

   • T: Virtual primary suppressed cells are made, which are the sum of some suppressed inner cells and which can be divided into two components. At least one component is singleton contributor. The other component may be an inner cell.

   • H: As T above. And in addition, the other component can be any primary suppressed published cell. This method may be computationally demanding for big data.

4. elimination (4th character):

   • t: The singleton problem will be handled by methodology implemented as a part of the Gaussian elimination algorithm.

   • m: As t above. And in addition, a message will be printed to inform about problematic singletons. Actual reveals will be calculated when singleton2Primary = T (1st character) and when singleton2Primary = t yield the same result as singleton2Primary = T. Problematic singletons can appear since the algorithm is not perfect in the sense that the elimination of rows may cause problems. Such problems can be a reason not to switch off sum2.

   • w: As m above, but warning instead of message.

   • T, M and W: As t, m and w above. In addition, the gauss elimination routine is allowed to run in parallel with different sortings so that the problem of eliminated singleton rows is reduced.

   • f: As F, which means that the elimination feature is turned off. However, when possible, a message will provide information about actual reveals, similar to m above.

5. combinations (5th character):

   • T: This is a sort of extension of singleton2Primary which is relevant when both integerUnique and elimination are used. For each unique singleton contributor, the method seeks to protect all linear combinations of singleton cells from the unique contributor. Instead of construction new primary cells, protection is achieved as a part of the elimination procedure. Technically this is implemented by extending the above elimination method. It cannot be guaranteed that all problems are solved, and this is a reason not to turn off singleton2Primary. Best performance is achieved when elimination is T, M or W.

   • t: As T, but without the added singleton protection. This means that protected linear combinations cannot be calculated linearly from non-suppressed cells. However, other contributors may still be able to recalculate these combinations using their own suppressed values.

Value

A character vector or NULL

References

Langsrud, Ø. (2024): “Secondary Cell Suppression by Gaussian Elimination: An Algorithm Suitable for Handling Issues with Zeros and Singletons”. Presented at: Privacy in statistical databases, Antibes, France. September 25-27, 2024. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1007/978-3-031-69651-0_6")}

Examples

NumSingleton("numTFF")
NumSingleton("numFtT")
NumSingleton("numttH")
NumSingleton("numTTFTT")

SSBtools documentation built on Oct. 30, 2024, 5:09 p.m.