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Frequently Asked Questions

What is data linkage?
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 creating links within and between 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). 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 linkageData Linkage: a 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’. process generates a set of indices sometimes called "linkage keys" that are stored by the 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’. 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 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). collections routinely linked by 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. 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 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. 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 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). 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 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..
What is the separation principle?
A separation principleThe separation of roles to ensure privacy is maintained, whereby identifiable information is kept separate to clinical/service information. The DLB strictly adheres to this principle and it must be maintained in all projects requesting linked data. 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 linkageData Linkage: a 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’. 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. 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). 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 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’. adds value to routinely collected 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)., 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 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. holds the "keys" to health and medical research in WA. The "chainAll of the linked records thought to belong to a single person. 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 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’. infrastructure.
What is linked data used for?
There are many applications for linked 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).:
- 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 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). 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 unidentifiableRelated to the identifiability of a dataset/data item; where the identity of a person/organisation is not immediately obvious and it is not reasonably possible to reidentify a person/organisation using other sources of information. data.

For more information please see our Access Policy.
How do I acknowledge the Data Linkage Branch and DOHWA in publications?
Acknowledging 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., Department of Health WA and other 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). 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 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’. 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 Merchant, the 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. Project Manager at alexandra.merchant@health.wa.gov.au
Who do I contact to discuss data variables?
Queries related to 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). 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 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). collections which are deemed to be identifiableRelated to the identifiability of a dataset/data item; where the identity of a person/organisation is immediately obvious. 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 Janine Alan 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 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).:
- 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 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. Project Manager (see Contacts page).
How will my data be delivered?
All complete 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). files are encrypted and burnt to disc, with the password emailed separately to the relevant analyst. All linked data must be collected from the 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. in person wherever possible. The recipient of the data will be required to sign a declaration acknowledging their responsibilities. Data recipients who are not based in Perth will have their encrypted data sent to them via a trackable Express Post satchel and will also be required to sign on collection.
How does the Data Linkage Branch ensure the validity of it's links?
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. employs a variety of approaches and tools to ensure that the links we make between records and chains are of the highest quality. For more information, check out our Linkage Quality page or download our Linkage Quality paper.
How do I request feedback on my draft outputs?
All draft outputs, regardless of format, resulting from the review of linked 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). must be sent to 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. and Custodians for review. Please allow two weeks for this review, or possibly longer if the output is very long (e.g. a student dissertation).
Please email your draft outputs to DataServices@health.wa.gov.au. A DLB Client Services staff member will coordinate the review of the material by Custodians on your behalf. The review will focus on:
• Impact on privacy and risk of reidentification of the data, including checking the suppression of low cell counts
• Issues relating to the data provided which may impact the interpretation of results, such as data quality, scope and coverage, and appropriateness of data items used
• Terminology and descriptions of data collections and linkageData Linkage: a 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’.
• Appropriate acknowledgements to data providers and DLB

DLB Client Services will provide any feedback via email. Any issues regarding privacy or inappropriate use of the data will be reported directly to DOH HRECDepartment of Health Human Research Ethics Committee. A group that provides governance over Department of Health personal health information and its use in research. See also http://ww2.health.wa.gov.au/Corporate/Articles/N_R/Research-ethics for consideration and liaison with the Principal Investigator.

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 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. Amendment Form via email and post in a hard copy of the new analyst’s confidentiality agreement/ acknowledgment.