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

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

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

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.

Hierarchies (1)

Hierarchies (2) Status narrow size class size class total size class S - L size class A - E size class % cells A frequency unsafe 32,842,052,961,4 D secondary unsafe 27,231,525,117,9 V safe 35,125,121,520,4 Status wide size class size class total size class S - L size class A - E size class % cells A frequency unsafe 32,841,149,361,4 D secondary unsafe 26,531,528,418,1 V safe 35,725,821,620,2

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

Historyfile, information loss and base material (2) Methods for determining information loss Cell valueFrequency Status 2 nd digit NACE 3 rd digit NACE 4 th digit NACE 5 th digit NACE 2 nd digit NACE 3 rd digit NACE 4 th digit NACE 5 th digit NACE A frequency unsafe B dominance unsafe D secondary unsafe V safe

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.