Definition: (p,q) rule

Category: Statistical methodologies

It is assumed that out of publicly available information the contribution of one individual to the cell total can be estimated to within q per cent (q=error before publication); after the publication of the statistic the value can be estimated to within ρ percent (p=error after publication). In the (p,q) rule the ratio p/q represents the information gain through publication. If the information gain is unacceptable the cell is declared as confidential. The parameter values ρ and q are determined by the statistical authority and thus define the acceptable level of information gain. In some NSIs the values of ρ and q are confidential. (Source: ESSNet SDC)

It is assumed that prior to publication of tabular data the contribution of one individual to a cell total can be estimated to within q per cent (a priori relative error in estimating the individual contribution). If after publication of the statistic the value can be estimated to within p per cent (a posteriori relative error in estimating the individual contribution), the cell is declared as confidential. The parameters p and q are determined by the statistical authority. In some NSIs the values of p and q are confidential. (Source: ESSnet "Memobust") http://ec.europa.eu/eurostat/ramon/statmanuals/files/SDC_Handbook.pdf Eurostat, ESSnet "Memobust", "Memobust Glossary" (part of the Memobust Handbook on Methodology of Modern Business Statistics), March 2014