Perturbation methods are procedures that are applied to data sets in order to protect the confidentiality of survey respondents. The goal of statistical disclosure control (SDC) is to provide accurate and useful data— especially public use data files—while also protecting confidentiality. Various methods have been suggested, and these may be classified two ways: (1) methods that do not alter the original data but reduce the amount of data released; and (2) methods that alter individual values while maintaining the reported level of detail. The first set of methods may be described as data coarsening; the second set of methods may be described as statistical perturbation methods.

Perturbation methods have the advantage of maintaining more of the actual data collected by survey respondents than data coarsening. Variables ...