Delivering the 2021 Census

Appendix A - Glossary

The terms below are in addition or complementary to the 2021 Census Dictionary Glossary.

Accessibility testing

Evaluating a product or service by testing how it can be easily used by people with disabilities. We aim to comply with WCAG standards with all our products.

Behavioural economics

A study of why people behave the way they do based on economics, psychology and emotions.

Culturally and linguistically diverse (CALD) populations

Australia’s population includes many people who were born overseas or have a parent born overseas and speak a variety of languages. Together, these groups of people are known as culturally and linguistically diverse (CALD) populations. 

Census day

Everyone in Australia is asked to fill in a Census form in relation to where they are residing on this day. For the 2021 Census, it was 10 August.  

Census instruction letter (CIL)

This letter is mailed to households with instructions and a code to complete the Census online and explains how to request a paper form if preferred.

Census reminder letter

This letter is mailed to households who have not yet responded to the Census. The letter contains instructions and a code to complete the Census online.

Census supporters

An organisation or person who promotes the Census within their community. Census supporters help by hosting information sessions or sharing Census information with their community.


The classifying of answers in each topic (group of Census questions) to a known list of answers so that counts can be published against them.

Data lake

A centralised repository designed to store, process and secure large amounts of structure, semi-structures and unstructured data.

Distributed Denial of Service (DDoS)

A cyber attack designed to load a network with so much malicious traffic that it cannot operate or communicate as it normally would. This causes the site's normal traffic, also known as legitimate packets, to come to a halt.


A structure which is intended to have people live in it, and which is habitable on Census day. Some examples of dwellings are houses, motels, flats, caravans, prisons, tents, humpies and houseboats. 

Field work

Work Census staff do outside of their homes such as knocking on doors, letter box drop or visiting establishments.

Household form

The Census household form (online or paper) is the primary means for collecting Census data and is used in all private dwellings. 

Imputation (persons)

Creating people counts and some basic demographics such as age and sex where the dwelling is determined to be occupied but didn’t respond to the Census.

Inclusive strategies

Strategies designed to ensure everyone is included in the Census regardless of their circumstances and where they are residing, their literacy or ability to complete a form. The strategies generally focused on improved engagement activities for awareness and supporting completion of the Census form.

Intelligent / Optical character recognition (in Census glossary)

Specialised computer software is used to interpret the handwriting on images taken of each page of the Census form. Once recognised, answers to Census questions are coded to the appropriate category of the relevant classification, for example Religion, Occupation, etc.

Interviewer household form (in Census glossary)

The Interviewer Household Form is used in Aboriginal and Torres Strait Islander communities (and areas where language differences or other factors make use of the standard self-enumeration forms impractical). It is an interview based Census form. 

Information Security Registered Assessment Program (IRAP)

The security service standard where independent assessors follow a multi-stage process to review all aspects of security for a product. Passing an IRAP assessment is a very strong sign of the security.

National Relay Service

Australian Government phone service for people who are deaf, have a hearing impairment and/or speech impairment and people wanting to communicate with them. 

Non-responding dwellings

Dwellings where a response has not yet been received, typically after Census day.

Occupancy determination

Determining if a dwelling will be/was occupied on Census day.

Penetration testing / ethical hacking

A security exercise where a cyber-security expert attempts to find vulnerabilities in a computer system. The purpose of this simulated attack is to identify any weak spots in a system’s defences which attackers could exploit.

Performance testing

Also called load testing, typically involves a simulated volume of traffic on a system to establish any break points and the systems total capacity.  

Personal form (in Census glossary)

The Census personal form (online or paper) records details for one person only. It contains the same questions as the Census household form but excludes the questions related to the dwelling. It is used for people staying in a non-private dwelling such as a hotel, motel, hostel, or nursing home or if a person in a private dwelling requests one for privacy or other purposes.

Social listening

Proactive listening to non-Census and non-ABS owned social media channels including public access forums and websites. The purpose is to:

  1. search for and identify possible areas of dis/mis/mal-information, and where appropriate intervene
  2. ensure communication is responsive to changing needs, interests and understanding of audiences and dispel misinformation.
Social media misinformation

Information that is false, but not created with the intention of causing harm. For example: A tweet saying that this year the Census can only be completed online.

Social media disinformation

Information that is false and deliberately created to harm a person, social group, organisation or country. For example: A post on a Facebook group saying that the Census sells your personal information and you should put in false data to protect yourself.

Social media malinformation

Information that is based on reality, used to inflict harm on a person, organisation, or country. For example: A post on Facebook saying that someone didn’t do the Census in 2016, didn’t get fined and encouraging others not to do the Census.

Special short form

Single page Census form mainly used for interviewing people experiencing homelessness.

Statistical impact

Something that has caused the data quality to be less reliable or accurate. Typically, it means the data hasn’t met an acceptable standard for release.

Statistical data quality

A measure of the data based on factors such as accuracy, completeness, consistency, reliability and whether it is up to date.

Usability testing

Evaluating a product or service by testing it with users. The goal is to identify any usability problems such as observing where the user becomes confused or follows an incorrect path.

Web Content Accessibility Guidelines (WCAG)

The Web Content Accessibility Guidelines (WCAG) is an internationally recognised standard created by the World Wide Web Consortium (W3C). The WCAG standard defines how to make web content more accessible to people with disabilities.

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