SCIPRESS J. Japan Statist. Soc.

J. Japan Statist. Soc., Vol. 32 (No. 1), pp. 107-117, 2002

Minimum Unsafe and Maximum Safe Sets of Variables for Disclosure Risk Assessment of Individual Records in a Microdata Set

Akimichi Takemura

Abstract. In the framework of disclosure control of a microdata set, a unique record is at risk of being identified. Even if a record is not unique in the microdata set, it may be considered risky if the frequency k of the cell, in which the record falls, is small. The notion of minimum unsafe combination introduced by Willenborg and de Waal (1996) is important in this respect. The purpose of this paper is to clarify the logical relationships between this notion and other closely related notions, and give an algorithm for obtaining relevant combinations of variables. We will define the minimum k-unsafe and maximum k-safe sets of variables for each record. We also give an illustration to show the usefulness of the proposed technique for the purpose of disclosure risk assessment and control.

Key words and phrases: Hasse diagram, hitting set problem, local suppression, NP-complete, sample unique.

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