The first Statistical Security Guide was released in 1995, says De Wolf. ‘In 2006, that guide was modified, because it had to be made shorter and a lot of examples were removed. We have recently revised the guide by making the texts easier to read and by updating the chapter on legislation and regulation in line with new legislation. This was necessary because of the introduction of the General Data Protection Regulation (in Dutch: AVG) in 2018 and a number of new EU regulations.’
Versions for internal and external use
The updated manual consists of two different versions: one for internal use and one to be shared with external users. ‘The internal version is provided for the statisticians of the various divisions within CBS who are responsible for the disclosure control of all statistics published. The published version is designed for researchers, ministries and knowledge institutions, such as the National Institute for Public Health and the Environment (RIVM). They frequently contact us with questions like “What rules does CBS apply when it comes to statistical disclosure control?” The guide is available in Dutch, but if there is sufficient demand, CBS will also provide an English version.’
Expert group for statistical disclosure control
There is also an expert group for statistical disclosure control at CBS, which colleagues from various disciplines participate in, as well as methodologists and lawyers, and the Data Protection Officer. They perform preparatory work on statistical disclosure control related to policy making.’ Peter-Paul de Wolf is also a member of this expert group. De Wolf is also involved in a variety of international working groups that include statistical disclosure control in their portfolios. One of those working groups advises on European statistics, in addition to providing input for software development. ‘For example, we look at the most effective ways to harmonise the disclosure control of census tables within the European Union.’ He also teaches courses on this subject in other countries.
Three elements
De Wolf recently wrote an interesting blog about his area of expertise for internal communications. ‘I see statistical disclosure control as a theme that is made up of three key elements: the rules, criteria and the involving methods. The rules are stated in the guide and reflect the general policy framework, the context of each particular statistic indicates which aspects are emphasised, and the criteria serve to verify compliance. However, context also matters when it comes to criteria. Last but not least, the methods help us to answer the question of how a publication that is not compliant can be published. While using a disclosure control method, we can reduce the risk of disclosure by rounding or rearranging the table, for example. In conclusion, statistical disclosure control requires a tailored approach.’
