Record Linkage Field Guide Goal: Find records in two datasets that refer to the same real-world person/entity. Process: Clean -> Block -> Compare -> Classify -> Evaluate Step 1: Clean Data Step 2: Blocking Blocking = split records into groups ( blocks ) by a blocking key, then compare records ""only within the same block**. It's grouping, not filtering: no record is removed, only pointless paris are skipped. 5H1W 5W1H Blocking Who records from both datasets What separate records into smaller groups When after cleaning, before detailed comparison Where comparisons happen only inside each block Why full comparison is too big and slow → smaller blocks are much faster How a rule (blocking key) decides the grouping Why Blocking? Problem: Comparing every pairs of records is too slow, and real data has millions of records. Without blocking: 100 x 100 = 10,000 comparisons With blocking: e.g. 1,000 compariso...