WA Data Linkage System Summary

January 2019
Total Number of Chains: 4,417,251*
Total number of records in the chains 114,807,453*
Maximum number of linked records in a chain 14,769*
Average chain length (excluding single record chains*) 26*
Total Number of Records Received this Month: 4,185,815*
Total Number of Records Linked this Month: 4,185,815*
*Note: singletons (people who only have one record in their ‘chain’) are not included in the total number of chains

The WA Data Linkage System (WADLS) is a system of linkages within and between data collections, maintained and operated by the Data Linkage Branch (DLB).

Since its modest beginnings in 1995, the WADLS has grown to become one of the most comprehensive, high quality and enduring linkage systems worldwide. Today it contains over 150 million records spanning over fifty routinely linked datasets.

Many of these datasets represent the Health sector, however a variety of non-Health datasets are also linked. Hundreds of other “project specific” datasets have also been linked in the WADLS over its lifetime.

The WADLS comprises a large database of demographic information, linkage keys and associated metadata, along with a linkage software package “DLS3” that is developed and supported by DLB’s in-house Systems Team.

DLB’s Linkage Officers implement linkage strategies using DLS3 and carry out a variety of quality checking protocols to ensure linkages are of a high quality.
More information about the WADLS and linkage quality can be found at: