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’. is a technique for connecting pieces of information that are thought to relate to the same person, family, place or event.

Information is created when a person comes into contact with certain services, for example, when they visit an emergency department, stay in a hospital or register the birth of their child.

If these different bits of information can be connected to a person, in a way that does not breach their privacy, it can all be used to produce evidence for improvements in the health of the WA community.

We need 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 because a person’s Medicare, Driver's licence and hospital patient numbers are all different and may not be able to connect information between different services.


Western Australian Data Linkage

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. links data in Western Australia. Data linkage techniques in WA have been developed to ensure the best possible 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. while at the same time protecting personal privacy. Since there are often millions of records being linked this way, highly specialised computer programs do most of the matching. For some of the more difficult matches a Linkage Officer will look at the records and make a decision about whether it is a true match.

There are two parts to records linked by the Data Linkage Branch.

  • Demographic data – this is identifiableRelated to the identifiability of a dataset/data item; where the identity of a person/organisation is immediately obvious. information such as a person’s name or address.
  • Clinical data – this is the information about what happened to the person, such as why they were in hospital.

Privacy is protected by separating this data before it is provided for linkage. This practice is known as the ‘separation principle’.

The Linkage Team within the Data Linkage Branch matches only the demographic information, and then makes a special key for each group of records that belongs to one person.

These keys can then be used to join up the clinical parts of the records, instead of a person’s name or other identifying information, for approved purposes. 

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The establishment and early development of data linkage for health services research in WA is described in "Population-based linkage of health records in Western Australia: development of a health services research linked database" (1999, PDF).

 If you are looking for more detailed information on how the Data Linkage Branch links its data, check out the technical Linkage Process page.


What Linked Data is Used For

Linked data is used in Western Australia to support approved research, develop policies, plan services and evaluate services. Research using linked data is very valuable and efficient because it includes all the people in WA, not small parts of the population. This provides a more complete picture of the health of people in WA. Linked data can be used for:

  • Tracking the use and re-use of Health Services, and modelling their potential future use. 
  • Research and later policy development into population based health services
  • Investigating potential projects i.e. testing hypotheses and pilot studies
  • As a capture-recapture tool, to improve the quality of datasets
  • For follow-up and comparison of different treatment regimes
  • To study the aetiology, co-morbidities and outcomes of disease


References to the creation and use of Linked Data in Australia can be found on the References Page.