File 24Although data linkageA complex technique for connecting data records within and between datasets using demographic data (e.g. name, date of birth, address, sex, medical record number). Also called ‘Record Linkage’ or ‘Linkage’. has been used for health and medical research in WA since the 1970s, the WA DataCan refer to: (1) the demographic data used in the Data Linkage process; or (2) information pertaining to services provided to people or their clinical information (available only from Data Custodians, including via CARES). Linkage System (WADLSWestern Australian Data Linkage System: The Western Australian system used to connect available health and other related information for the WA population. This incorporates database tables holding demographic data and linkage keys, and the bespoke tools used by Linkage Staff to process, create, store and retrieve them.) was formally established in 1995 as a collaboration between the WA Department of Health (DOH), University of Western Australia (UWAUniversity of Western Australia), Telethon Kids Institute (then the Telethon Institute for Child Health Research) and Curtin University. Recognising the potential community benefit of using linked, de-identified Health data for research, the initial setup and operational costs of the WADLS were met through grant funding from the WA Lotteries Commission. In 1997 the DOH took over as majority funder and the Data Linkage Unit (later renamed the Data Linkage BranchThe specialist team at the Department of Health who are responsible for developing and maintaining the WA Data Linkage System, performing data linkage, and the facilitation of access to linked data., DLBData Linkage Branch: the specialist team at the Department of Health who are responsible for developing and maintaining the WA Data Linkage System, performing data linkage, and the facilitation of access to linked data.) was established.


The DLB manages the WADLS, which entails the creation and maintenance of linkages within and between a wide range of Health and other datasets. These linkages use rigorous, internationally accepted privacy preserving protocols, probabilisticProbabilistic linkage is a method of linking records using non-unique identifiers (e.g. name, date of birth) to establish weights which represent the likelihood that two records belong to the same person. These weight are used to inform matches and non-matches, and can include clerical review for a selected 'grey area' in between. matchingA part of the linkage process whereby blocked pairs of records are compared, according to user-set parameters, to determine the strength of the match., clerical reviewThe process whereby potential matches that do not match strongly enough to automatically match, nor weakly enough to automatically discard, are manually evaluated by a Linkage Officer. and quality controlA process that examines an extract of data for completeness and correctness. This includes checking file counts, consistency of roots, presence of requested fields, overlap between groups, field formatting and the correct application of inclusion/exclusion criteria. mechanisms to create a robust and complex system of links between otherwise disparate pieces of individual information. Linked de-identified data can be requested for ethically approved research, planning and evaluation projects which show benefit to the lives of Western Australians.


The size of DLB has increased significantly over the years: a Database Manager (later Manager, Data Linkage Systems) was introduced in 1998 followed by a Branch Program Manager in 2000, along with Linkage Officers, Software Developers, Client Services staff and Data Analysts at various times throughout the Branch’s history. Until 2007, DLB was staffed by all four contributing institutions – DOH, UWA, Telethon Kids and Curtin – when the Branch was fully centralised and all roles transitioned to DOH positions.


As of 2016, the DLB comprises 17 staff divided into two teams: Linkage & Systems and Client Services & Data Delivery. These teams work in physically separate areas of the floor to ensure that privacy protecting role separationThe practice of separating access to identifiable information from clinical or service information. e.g. within a Project Team, one person manages the identifiable information of consenting participants. Another member of the team analyses and manages the deidentified health service information. Neither member has access to both sets of information. is maintained in all DLB practices, although the teams are in constant communication to ensure a harmonious system. DLB’s staff members come from a wide range of background disciplines, including health science, mathematics, computer science, information management, medicine and education.


DLB has been a pioneer of innovation in Data Linkage techniques and surrounding processes and protocols. Examples include:

  • The development of assorted value-adding data enhancements, such as geocodingThe process of assigning a geographical coordinate to a named feature. In the case of the feature being a street address, the address must first be matched to a known address in a spatially referenced dataset such as those maintained by Landgate (in WA) and Australia Post. Once a geographical coordinate has been assigned to the feature, census statistical areas (SA1, SA2, LGA) can be derived. functions and related spatial data (1997), the family connectionsA link that connects people who belong to the same family (e.g. mother, father, sibling, cousin), provided as a list of pairs of related ROOTS and their relation type. system and genealogicalRelating to the history of a person, family or group. links (2007), and the derived indigenous status flagA DLB-created value that represents a ‘best guess’ of the indigenous status of a person, via an algorithm which collects indigenous status information from various records in a linkage chain to calculate a single result. Formerly known as the ‘Getting Our Story Right (GOSR) flag’. (2012);
  • Linkages of non-government datasets, including St John Ambulance (2001), Silver ChainAll of the linked records thought to belong to a single person. Nursing Association (2003) and Brightwater Care Group (2016);
  • The introduction of a Client Services Team in 2005 and formalised application process in 2008, which has supported hundreds of projects relating to planning, service evaluation and research;
  • Pioneering cross-agency linkages with the Registry of Births, Deaths and Marriages (1996) and State Electoral Commission (1999), and later via the Road Safety Project and Developmental Pathways Project (both 2006);
  • Undertaking the first linkage of Commonwealth MBS/PBS data in 2004;
  • Streamlining the delivery of linked data through the Custodian Administered Research Extract ServerA DLB initiative that streamlines linked data extraction, quality control and delivery services. (CARESCustodian Administered Research Extract Server: a DLB initiative that streamlines linked data extraction, quality control and delivery services.) in 2013;
  • Publicly available activity metrics (since 2015);
  • The rapid and continuous growth of the WADLS, from 4 routinely linked datasets in 1995 to over 40 in 2016 – collectively comprising almost one hundred million records!


Since 2015, DLB has undergone a period of significant change. This began with the retirement of Diana Rosman and Carol Garfield, two foundational members of the Branch, and the introduction of Janine Alan as DLB’s new Branch Manager. As of 2016, DLB has moved to a new Division within the DOH, with several exciting developments ahead:

  • The continued use and expansion of the advanced linkage system “DLS3”;
  • The introduction of our new geocoding platform “Spectrum”;
  • Continuation of DLB ‘s Researcher Training Course;
  • Opportunities to expand the family connections system;
  • Continued expansion of WADLS and CARES, with several new datasets due to be added in 2016/17.


The first twenty years of DLB were an exceptional success and the Branch looks forward to another twenty years (and more!) of innovation, partnership and exceptional service delivery