An evolutionary algorithm to enhance multivariate Post-Randomization Method (PRAM) protections

The amount of public statistical information available is growing and more accurate protection methods are needed in order to achieve data confidentiality. The Post-Randomization Method (PRAM) protection method was introduced in 1997 as a very powerful method for categorical microdata, but it is still not widely used. This method has a Markov matrix as a parameter. The main problem of the application of this method is that it is difficult to find a good Markov matrix that performs changes in the microdata file producing low loss of valuable information and low risk of disclosure of sensitive data.In this paper we present a methodology that helps us to find a matrix to perform better protections. This is achieved by using an evolutionary algorithm with integrated Information Loss and Disclosure Risk measures. Experiments using three different datasets are also presented in order to empirically evaluate the application of this technique.