Scope and study population

The scope of the analyses was limited to people aged 15 years and over living in Australia in occupied private dwellings on Census Night. Children under the age of 15 were excluded as some questions in the Census are only asked of people aged 15 and over.

This project excluded unoccupied private dwellings, people who live in non-private dwellings or Migratory, offshore and shipping SA1s, non-classifiable households or Visitor only households, as these are out of scope for many of the social and economic variables in the Census. Overseas visitors were also excluded as they are out of scope for the Census CALD variables.

Although Aboriginal and Torres Strait Islander (First Nations) people are diverse in language and culture, their experiences and needs are unique and are therefore considered distinct from the CALD population for the purposes of this report. Information about the health and wellbeing of First Nations people can be viewed at First Nations people.

Assessment of behavioural and biomedical health risk factors as explanatory factors is also out of scope for this report as information was not collected in the Census.

This scope formed the basis of the study population for all analyses in the report. However, the study population was further restricted to valid responses to the Census questions for the variables used in each set of regression models used in the modelling component of the report:

  • long-term health conditions 
  • age and the social determinants of health
  • specific CALD variables of interest for each set of regression models.

Each set of the regression models used different CALD variables, but the same long-term health condition and social determinant of health variables. The number of invalid responses to the long-term health condition questions are based on a single Census question. Therefore, the sample size in each set of analyses differed depending on the CALD variables of interest.

The set of models that used the country of birth or the languages used at home included specific countries of birth and languages, respectively. Country and language groups with a denominator less than 30 or a numerator less than 20 for a selected long-term health condition were excluded from the analyses. This exclusion criteria resulted in different specific country and language groups for females and males depending on the long-term health condition, so sample sizes differed in each set of analysis depending on sex and each long-term health condition variable.


People who did not provide a response to the long-term health condition question or the CALD variables in the 2021 Census were excluded from these analyses. The ABS provides item non-response rates for person-level items in their Guide to the Census (Understanding data quality: Item non-response rates). The person-level non-response rates for the long-term health conditions and CALD variables used in these analyses are provided below.

Table 9: Item non-response rates from 2021 Census


Item non-response (%)

Count of selected long-term health conditions


Country of birth of person


Language used at home


Proficiency in spoken English


Year of arrival in Australia


For more details, please see Understanding data quality: Item non-response rates.