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Frequently Asked Questions

What is data linkage?
Data linkageThe process of establishing whether two or more pieces of information belong to or describe the same person, family, event, place or time period. is a technique for creating links within and between data sources so that information that is thought to relate to the same person, family, place or event can be connected for analysis.
What is a Linkage Key?
The linkage process generates a set of indices sometimes called "linkage keys" that are stored by the Data LinkageThe process of establishing whether two or more pieces of information belong to or describe the same person, family, event, place or time period. Unit in a Links Table. These "linkage keys" are held separately from any personal demographic information and they enable related health-related records to be joined together for approved research projects.
What datasets are linked?
The data collections routinely linked by the Data LinkageThe process of establishing whether two or more pieces of information belong to or describe the same person, family, event, place or time period. Branch are:
- Midwives Notifications
- Cancer Registrations
- Mental Health contacts
- Hospital Admissions
- Emergency Presentations
- Electoral Roll
- Birth Registrations
- Death Registrations
- Marriage Registrations (for linkage only, not available for research)
Electoral, birth and death records are linked routinely under a special arrangement with the WA Electoral Commission and the Registry of Births, Deaths and Marriages.

Updates to the links are ongoing and new demographic information is received on a regular basis. This ensures that the links in the WADLSThe Western Australian Data Linkage System creates and stores links within and between the state's health data collections. The WADLS does not contain any clinical or service data, rather it consists of groups of links called chains. remain as up to date as possible. For more information on the datasets currently linked please see our Data Collections page.
What is "core" data?
We refer to the population health data collections managed within the Department of Health WA as the "core" data. Electoral records and birth, death registrations are also considered to be "core" data for the WADLSThe Western Australian Data Linkage System creates and stores links within and between the state's health data collections. The WADLS does not contain any clinical or service data, rather it consists of groups of links called chains..
What is the separation principle?
A separation principle was developed to address privacy concerns and enable data custodians to retain control over access to information in their care. This protocol is now referred to as "best practice protocol" and is used widely by number of linkage centres across the country.

The principle consists of four distinct steps. In this way, access to identifying information is restricted to a specialised linkage team who perform the first and second steps. Data custodians are involved in the third step. Researchers are only involved in the last step and therefore do not need to access any personal identifying information.
1. Linkage staff create, store and manage links in a dynamic Linkage System using confidential personal demographic information.
2. Linkage staff extract subsets of links from the linkage system, then encrypt these “linkage keys” differently for each particular project.
3. Encrypted “linkage keys” are provided to the custodians (of the separate datasets) so they can add them to their clinical or service details for that particular project.
4. Lastly, researchers receive clinical or service details from each data custodian and use the encrypted keys to connect the details needed for their analyses.
Why is data linkage useful?
Data linkageThe process of establishing whether two or more pieces of information belong to or describe the same person, family, event, place or time period. adds value to routinely collected data, because the information required to study complex diseases is rarely found in one place. Epidemiologists and population health and health services researchers need to study many factors to make sure their research is meaningful.

It is fair to say that the WADLSThe Western Australian Data Linkage System creates and stores links within and between the state's health data collections. The WADLS does not contain any clinical or service data, rather it consists of groups of links called chains. holds the "keys" to health and medical research in WA. The "chainA group of links that have been determined to relate to one individual. of links" design of the WADLS has enabled it to be easily updated and expanded. The system now plays an important part in helping many researchers to discover what makes people healthy. It is an extremely valuable research tool for academics, policy planners and analysts.
How is the Data Linkage Branch funded?
Funding is provided by the Department of Health WA, other state agencies, the Road Trauma Trust Fund, the Australian Government and contributions from NHMRC & ARC research grants. There is also a substantial in-kind contribution from our Centre of Excellence partners.

Costs may be recovered where work falls outside our core activities and this revenue contributes to the on-going development of the data linkageThe process of establishing whether two or more pieces of information belong to or describe the same person, family, event, place or time period. infrastructure.
What is linked data used for?
There are many applications for linked data:
- Population based health research and policy development
- To investigate 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
Who can use linked data?
Access to linked data is granted to researchers who:
- Have obtained approval from the relevant Data Custodians to ensure the data requested is appropriate for the purpose of the research.
- Have obtained approval from the relevant Human Research Ethics Committee(s) to conduct their proposed research,
Strict protocols must be followed to ensure the confidentiality and security of linked data, and wherever possible, research should be performed using unidentifiableWhere identifiers (e.g. name, address, full date of birth) have been removed and there is no means to reidentify specific individuals. data.

For more information please see our Access Policy.
How do I acknowledge the Data Linkage Branch and DOHWA in publications?
Acknowledging the Data LinkageThe process of establishing whether two or more pieces of information belong to or describe the same person, family, event, place or time period. Branch, Department of Health WA and other data collections in publications is part of the Access Policy and undertakings signed to by Principal Investigators. The acknowledgment will vary according to the individual project, but here are some examples:
- Acknowledgement 1: Standard Project
  The authors wish to thank the staff at the Western Australian Data Linkage Branch and [insert names of Data Collections involved].
- Acknowledgement 2: More complex project
  The authors wish to thank the Linkage and Client Services Teams at the Western Australian Data Linkage Branch, in particular [insert names of staff who provided extra help], as well as [insert names of Data Collections/Custodians involved].

How do I add/remove personnel to my project?

There is something wrong with my data, who do I contact?
Please contact Alex Godfrey, the DLB Project Manager at alexandra.godfrey@health.wa.gov.au
Who do I contact to discuss data variables?
Queries related to data variablesThe specific data items that are collected for health records, e.g. name, address, date of birth, sex etc. Researchers can apply to obtain certain variables from DOHWA data collections. The release of these variables is decided by the individual data custodians of those collections. should be directed to the relevant individual Data Managers. For further information please see the Contacts page at the Department of Health website.
Why can’t I access certain variables?
There are some variablesThe specific data items that are collected for health records, e.g. name, address, date of birth, sex etc. Researchers can apply to obtain certain variables from DOHWA data collections. The release of these variables is decided by the individual data custodians of those collections. contained in the data collections which are deemed to be identifiableWhere the identity of an individual can be reasonably ascertained, e.g. name, address, full date of birth. or potentially identifiable (e.g. name, full date of birth, address). The National Health and Medical Research Council (NHMRC) National Statement states that the public benefit of using personal health information must outweigh the risk to privacy; therefore wherever possible only non-identifiable data can be released for medical and health research.
What am I allowed to release in publications?
No information that will directly or indirectly identify individuals should be released in publications. When there are a small number of people in a study group, be careful about describing details (e.g. cause of death) in the text. The same applies to tables, graphs and maps. If you have any queries about what you can include in your publication, please contact Diana Rosman on (08) 9222 4261.
Which datasets can I obtain SEIFA/ARIA codes for?
SEIFASocio-Economic Indexes for Area. These values are assigned to geocoded areas and measure socioeconomic conditions. SEIFA codes can be assigned using 1996, 2001 and 2006 ABS census data./ARIAAccessibility/Remoteness Index of Australia. These values are assigned to geocoded areas and measure geographic remoteness. ARIA codes can be assigned using 1996, 2001 and 2006 ABS census data. codes can be added to the datasets which are routinely geocoded, using the ABS areas for 1996, 2001 and 2006 census data:
- Emergency Department Data Collection
- Death Register
- Hospital Morbidity Data Collection
- Midwives Notification Scheme
I have discovered a breach in protocol, what do I do?
Please contact a member of the Client Services Team (see the Contacts) for advice.
How do I know the progress of my project?
To ask about the status of your project please contact the DLB Project Manager (see Contacts page).

DOHWADepartment of Health Western Australia HREC approved	Principal Investigator to submit the DOHWA HREC Amendment Form to the Executive Officer via email (HREC@health.wa.gov.au) and post in a hard copy of the new personnel’s confidentiality agreement/acknowledgment.
No DOHWA HREC approval	Principal Investigator to submit the DLB Amendment Form via email and post in a hard copy of the new analyst’s confidentiality agreement/ acknowledgment.