ESSNET-SDC Deliverable Blocking Methods for Microdata Protection

Blocking is a well-known technique used to partition a set of records into several subsets of manageable size. The standard approach to blocking is to split the records according to the values of one or several attributes (called blocking attributes). This report presents a new blocking method based on 2-trees for intelligently partitioning very large data sets. Blocking makes sense whenever the treatment to be used on the data set is of complexity higher than linear. We take here microaggregation (which has quadratic complexity) as a treatment, but other superlinear treatments can benefit from the blocking method described (like record linkage, also of quadratic complexity).