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 p 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 p and q are determined by the statistical authority and, thus, define the acceptable level of information gain. In some [National Statistical Organizations] the values of p and q are confidential.
NIST SP 800-188 from OECD Glossary of Statistical Terms