Blurring replaces a reported value by an average. There are many possible ways to implement blurring. Groups of records for averaging may be formed by matching on other variables or by sorting on the variable of interest. The number of records in a group (whose data will be averaged) may be fixed or random. The average associated with a particular group may be assigned to all members of a group, or to the "middle" member (as in a moving average). It may be performed on more than one variable with different groupings for each variable.
ESSNet SDC (Network of Excellence in the European Statistical System in the field of Statistical Disclosure Control), under the coordination of Anco HUNDEPOOL, "Handbook on Statistical Disclosure Control", version 1.2 (2010 Edition)