IMPROVING CONFIDENTIALITY WITH tau-ARGUS BY FOCUSSING ON CLEVER USAGE OF MICRODATA

1. IMPROVING CONFIDENTIALITY WITH tau-ARGUS BY FOCUSSING ON CLEVER USAGE OF MICRODATA Roland van der Meijden MSc. ± 10 minutes

2. Content of presentation • tau-Argus • Tuning possibilities • Hierarchies • Historyfile, information loss and base material • Conclusions

3. Tau-Argus • Automated cell suppression software • Calculates confidentiality effects on all dimensions of a table simultaneously • Offers 4 confidentiality rules: • (n,k)-rule / dominance rule • p%-rule • p-q-rule / prior-posterior-rule • Minimum frequency rule

4. Tuning possibilities • Hierarchies: The way hierarchies are built is of influence on how secondary suppressions are applied. • History file: A preference can be given for which cells may or must be secondarily confidential. • Information loss weights: Information will be lost when applying secondary suppressions. The way tau-Argus calculates this information loss can be adjusted. • Base material: The way the microdata and preferred output are composed is of influence on the way secondary suppressions are applied.

5. Hierarchies (1)

6. Hierarchies (2)

7. Historyfile, information loss and base material (1) • Historyfile • Confidential, publishable, preferably do (not) suppress secondarily • Information loss • Cell value, frequency, equal and distance • Base material • Small area estimation, deliberately adjusting microdata and coordination of publication obligations

8. Historyfile, information loss and base material (2)

9. Conclusions • tau-Argus is a tool that is helpful in calculating confidentiality effects. • The confidentiality pattern can be influenced. • Improving the confidentiality pattern, takes a lot of effort. • Both tooling and the way base material is used are of influence on the confidentiality pattern.