Introduction to Statistical Disclosure Control

Statistical offices basically release two kinds of data, namely tabular data and microdata. Tabular data are the traditional products of statistical offices. These tables contain aggregated data. Microdata sets are released only since recently. These microdata sets consist of records with information about individual entities, such as persons or business enterprises, and have generally been collected by means of a survey. In other words, each record contains the values of a number of variables for an individual entity. A microdata set is in fact the raw material that is used to construct tables. In former days they were actually only used for constructing tables which were subsequently released. Nowadays, the microdata sets themselves are also released, although usually in a somewhat adapted form. Because the disclosure risk for microdata is potentially much higher than that for tables, this is an important reason for the increasing attention that SDC demands.