Government statistical agencies often apply statistical disclosure limitation
techniques to survey microdata to protect the confidentiality of respondents.
There is a need for valid and practical ways to assess the protection provided.
This paper develops some simple methods for disclosure limitation techniques
which perturb the values of categorical identifying variables. The methods are
applied in numerical experiments based upon census data from the United Kingdom
which are subject to two perturbation techniques: data swapping (random and
targeted) and the post randomization method.