12/16 month rule
Under a '12/16 month rule', incoming overseas travellers (who are not currently counted in the population) must be resident in Australia for a total period of 12 months or more, during the 16 month follow-up period to then be added to the estimated resident population. Similarly, those travellers departing Australia (who are currently counted in the population) must be absent from Australia for a total of 12 months or more during the 16 month follow-up period to then be subtracted from the estimated resident population.
The 12/16 month rule does not have to be continuous and takes account of those persons who may have left Australia briefly and returned, while still being resident for 12 months out of 16. Similarly, it takes account of Australians who live most of the time overseas but periodically return to Australia for short periods.
Average annual rate of growth
The average annual growth rate, r, is calculated as a percentage using the formula:
where P0 is the population at the start of the period, Pn is the population at the end of the period and n is the length of the period between P0 and Pn in years.
Refers to people born Post-World War II between the years 1946 and 1964.
The delivery of a child, irrespective of the duration of pregnancy, who, after being born, breathes or shows any other evidence of life such as heartbeat.
The complete enumeration of a population at a point in time with respect to well-defined characteristics (e.g. Persons, Manufacturing, etc.). When the word is capitalised, "Census" refers to the national Census of Population and Housing.
Death is the permanent disappearance of all evidence of life after birth has taken place. The definition excludes deaths prior to live birth.
For the purposes of the Deaths and Causes of Death collections compiled by the ABS, a death refers to any death which occurs in, or en route to Australia and is registered with a state or territory Registry of Births, Deaths and Marriages.
Estimated resident population (ERP)
The official measure of the population of Australia is based on the concept of usual residence. It refers to all people, regardless of nationality, citizenship or legal status, who usually live in Australia, with the exception of foreign diplomatic personnel and their families. It includes usual residents who are overseas for less than 12 months over a 16-month period. It excludes overseas visitors who are in Australia for less than 12 months over a 16-month period.
Estimates of the Australian resident population are generated on a quarterly basis by adding natural increase (the excess of births over deaths) and net overseas migration (NOM) occurring during the period to the population at the beginning of each period. This is known as the cohort component method, and can be represented by the following equation:
Pt+1 = Pt + B - D + NOM, where:
Pt = the estimated resident population at time point t
Pt+1 = the estimated resident population at time point t+1
B = the number of births occurring between t and t+1
D = the number of deaths occurring between t and t+1
NOM = net overseas migration occurring between t and t+1.
For state and territory population estimates, an additional term is added to the equation representing net interstate migration (NIM) occurring between t and t+1, represented by the following equation:
Pt+1 = Pt + B - D + NOM + NIM.
Greater Capital City Statistical Area (GCCSA)
Represent the socioeconomic area of each of the eight state and territory capital cities. These boundaries are built from aggregations of whole Statistical Areas Level 4. GCCSA boundaries represent a broad socioeconomic definition of each capital city, they contain not only the urban area of the capital city, but also surrounding and non-urban areas where much of the population has strong links to the capital city, through for example, commuting to work.
A household is a group of two or more related or unrelated people who usually reside in the same dwelling who regard themselves as a household and who make common provision for food or other essentials for living; or a person living in a dwelling who makes provision for his or her own food and other essentials for living, without combining with any other person. Households include group households of unrelated persons, same-sex couple households, single-parent households as well as one-person households.
A household usually resides in a private dwelling (including caravans etc. in caravan parks). Persons usually resident in non-private dwellings, such as hotels, motels, boarding houses, gaols and hospitals, are not included in household estimates.
This definition of a household is consistent with the definition used in the Census.
An infant death is the death of a live-born child who dies before reaching his/her first birthday.
Infant mortality rate (IMR)
The number of deaths of children under one year of age in a financial year per 1,000 live births in the same financial year.
Intercensal difference is the difference between two estimates at 30 June of a Census year population: the first based on the latest Census, and the second arrived at by updating the 30 June estimate of the previous Census year with intercensal components of population change. It is caused by differences in the start and/or finish population estimates and/or in estimates of births, deaths or migration in the intervening period which cannot be attributed to a particular source. For further information see Population Estimates: Concepts, Sources and Methods, 2009 (cat. no. 3228.0.55.001).
For any distribution, the median value is that which divides the relevant population into two equal parts, half falling below the value, and half exceeding it. Thus, the median age is the age at which half the population is older and half is younger.
Prior to September quarter 2006, the ABS applied a number of adjustments to overseas arrivals and departures data in order to produce estimates of net overseas migration (NOM). These mainly comprised adjustments designed to reflect differences between stated travel intentions and actual travel behaviour. Until recently, adjustments used by ABS to produce NOM estimates were collectively referred to as 'category jumping adjustments'. They are now referred to more simply as 'migration adjustments'.
Excess of births over deaths.
Net interstate migration
The difference between the number of persons who have changed their place of usual residence by moving into a given state or territory and the number who have changed their place of usual residence by moving out of that state or territory during a specified time period. This difference can be either positive or negative.
Net overseas migration (NOM)
Net overseas migration is the net gain or loss of population through immigration to Australia and emigration from Australia. Under the current method for estimating final net overseas migration this term is based on a traveller's actual duration of stay or absence using the '12/16 month rule'. Preliminary NOM estimates are modelled on patterns of traveller behaviours observed in final NOM estimates for the same period one year earlier. NOM is:
- based on an international traveller's duration of stay being in or out of Australia for 12 months or more over a 16-month period;
- the difference between:
- the number of incoming international travellers who stay in Australia for 12 months or more over a 16-month period, who are not currently counted within the population, and are then added to the population (NOM arrivals); and
- the number of outgoing international travellers (Australian residents and long-term visitors to Australia) who leave Australia for 12 months or more over a 16-month period, who are currently counted within the population, and are then subtracted from the population (NOM departures).
NOM arrivals are all overseas arrivals that contribute to net overseas migration (NOM). It is the number of incoming international travellers who stay in Australia for 12 months or more over a 16-month period, who
currently counted within the population, and are then added to the population.
Under the current method for estimating final net overseas migration this term is based on a traveller's actual
duration of stay or absence using the '12/16 month rule'.
NOM departures are all overseas departures that contribute to net overseas migration (NOM). It is the number of outgoing international travellers who leave Australia for 12 months or more over a 16-month period, who are
currently counted within the population, and are then subtracted from the population.
Under the current method for estimating final net overseas migration this term is based on a traveller's
duration of stay or absence using the '12/16 month rule'.
The difference between the actual Census count (including imputations) and an estimate of the number of people who should have been counted in the Census. This estimate is based on the Post Enumeration Survey (PES) conducted after each Census. For a category of person (e.g. based on age, sex and state of usual residence), net undercount is the result of Census undercount, overcount, differences in classification between the PES and Census and imputation error.
For Australia, population growth is the sum of natural increase and net overseas migration. For states and territories, population growth also includes net interstate migration. After the Census, intercensal population growth also includes an allowance for intercensal difference.
Population growth rate
Population change over a period as a proportion (percentage) of the population at the beginning of the period.
The ABS uses the cohort-component method for producing population projections of Australia, the states, territories, capital cities and balances of state. This method begins with a base population for each sex by single year of age and advances it year by year, for each year in the projection period, by applying assumptions regarding future fertility, mortality and migration. The assumptions are based on demographic trends over the past decade and longer, both in Australia and internationally. The projections are not predictions or forecasts, but are simply illustrations of the change in population which would occur if the assumptions were to prevail over the projection period. A number of projections are produced by the ABS to show a range of possible future outcomes.
Post Enumeration Survey (PES)
The Census Post Enumeration Survey (PES) is a household survey conducted following the Census. The PES allows the ABS to estimate the number of people missed in the Census and the number counted more than once or in error. Historically more people are missed than are counted more than once in Australia, leading to a net undercount. Results from the PES contribute to a more accurate calculation of the estimated resident population (ERP) for Australia and the states and territories, which is then backdated to 30 June of the Census year.
Rebasing of population estimates
After each Census, the ABS uses Census counts by place of usual residence which are adjusted for undercount to construct a new base population figure for 30 June of the Census year. Because this new population estimate uses the Census as its main data source, it is said to be 'based' on that Census and is referred to as a population base.
Rebasing refers to the process by which the ABS uses this new base to update all previously published quarterly population estimates from the previous census to the most recent census (the intercensal period). For further information on rebasing to the 2016 Census see Australian Demographic Statistics, December quarter 2016
(cat. no. 3101.0) Feature Article: Preliminary Rebasing of Australia's Population Estimates using the 2016 Census of Population and Housing.
Recasting of population estimates
The recasting of ERP was a one-off process undertaken during the course of rebasing to the 2011 Census. The decision to recast historical ERP data from September 1991 to June 2006 was in response to the unusually high preliminary intercensal difference, resulting from a change in the methodology used to estimate undercount in the 2011 Census. For further information see Australian Demographic Statistics, December quarter 2012 (cat. no. 3101.0)
Feature Article: Final Rebasing of Australia's Population Estimates, September Quarter 2006 - June Quarter 2011
and Recasting 20 Years of ERP.
The sex ratio relates to the number of males per 100 females. The sex ratio is defined for the total population, at birth, at death and among age groups by appropriately selecting the numerator and the denominator of the ratio.
Significant Urban Area (SUA)
Aggregations of whole Statistical Areas Level 2 to define and contain major urban and near-urban concentrations of over 10,000 people. They include the urban population, any immediately associated populations, and may incorporate together one or more closely associated Urban Centre and Localities and the areas between. They are designed to incorporate any likely growth over the next 20 years. SUAs do not cover the whole of Australia, and may cross State boundaries.
Standardised death rate (SDR)
Standardised death rates enable the comparison of death rates between populations with different age structures by relating them to a standard population. The current standard population is all persons in the Australian population at 30 June 2001 (19,413,240), as published prior to recasting the ERP series. SDRs are expressed per 1,000 or 100,000 persons. There are two methods of calculating SDRs:
State or territory of usual residence
- The direct method - this is used when the populations under study are large and the age-specific death rates are reliable. It is the overall death rate that would have prevailed in the standard population if it had experienced at each age the death rates of the population under study; and
- The indirect method - this is used when the populations under study are small and the age-specific death rates are unreliable or not known. It is an adjustment to the crude death rate of the standard population to account for the variation between the actual number of deaths in the population under study and the number of deaths which would have occurred if the population under study had experienced the age-specific death rates of the standard population.
State or territory of usual residence refers to the state or territory of usual residence of:
- the population (estimated resident population);
- the mother (birth collection); and
- the deceased (death collection).
In the case of overseas movements, state or territory of usual residence refers to the state or territory regarded by the traveller as the one in which he/she lives or has lived. State or territory of intended residence is derived from the intended address given by overseas arrivals, and by Australian residents returning after a journey abroad. Particularly in the case of the former, this is not necessarily the state or territory in which the traveller will eventually establish a permanent residence.
Total fertility rate (TFR)
The sum of age-specific fertility rates (live births at each age of mother per female population of that age) divided by 1,000. It represents the number of children a female would bear during her lifetime if she experienced current age-specific fertility rates at each age of her reproductive life (ages 15 - 49).
Usual residence within Australia refers to that address at which the person has lived or intends to live for a total of six months or more in a given reference year.