GLOSSARY
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.
Australian Statistical Geography Standard (ASGS)
The ASGS brings all the regions for which the ABS publishes statistics within the one framework and has been in use for the collection and dissemination of geographically classified statistics since 1 July 2011. It is the current framework for understanding and interpreting the geographical context of statistics published by the ABS. For further information see Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Statistical Areas, July 2016 (cat. no. 1270.0.55.001).
Age-dependency ratio
The dependency ratio is a measure used to compare the size of the 'working age' population to the size of the non-working age population, calculated as the sum of people aged 0-14 and 65 years and over divided by the number of people aged 15-64 years, multiplied by 100.
Age-specific death rates
Age-specific death rates are the number of deaths (on either an occurred or registered basis) during the calendar year at a specified age per 1,000 of the estimated resident population of the same age at mid-point of the year (30 June). Pro rata adjustment is made in respect of deaths for which the age of the deceased is not given.
Age-specific fertility rates
Age-specific fertility rates are the number of live births occurring during the calendar year, according to the age of the mother, per 1,000 of the female estimated resident population of the same age at 30 June. For calculating these rates, births to mothers under 15 years are included in the 15 year–old age group, and births to mothers aged 50 years and over are included in the 49 year–old age group.
Average annual growth rate
The average annual population growth rate, r, is calculated as a percentage using the formula:
r =
where P_{0} is the population at the start of the period, P_{n} is the population at the end of the period and n is the length of the period between P_{n} and P_{0} in years.
Baby boomers
Refers to people born Post-World War II between the years 1946 and 1964.
Birth
The delivery of a child, irrespective of the duration of pregnancy, who, after being born, breathes or shows any evidence of life such as a heartbeat.
Capital city
Refers to the Greater Capital City Statistical Areas of states and territories as defined in the Australian Statistical Geography Standard.
Census
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
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
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:
P_{t+1} = P_{t} + B - D + NOM, where:
P_{t} = the estimated resident population at time point t
P_{t+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:
P_{t+1} = P_{t} + B - D + NOM + NIM.
Fastest growth
Based on the rate of change in population over a period (expressed as a percentage). See population growth rate.
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. For further information see Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Statistical Areas, July 2016 (cat. no. 1270.0.55.001).
Interstate migration
The movement of people over a state or territory boundary for the purpose of changing their place of usual residence. Net interstate migration is the difference between arrivals and departures and can be either positive or negative.
Largest growth
Based on absolute change in population over a period.
Life expectancy
Life expectancy refers to the average number of additional years a person of a given age and sex might expect to live if the age-specific death rates of the given period continued throughout his or her lifetime.
Life Table
A life table is a statistical model used to represent the mortality experience of a population. In its simplest form, a life table is generated from age-specific death rates and the resulting values are used to measure mortality, survivorship and life expectancy. The life table functions relevant to population projections are:
- qx - the proportion of persons dying between exact age x and exact age x+1. It is the mortality rate, from which other functions of the life table are derived; and
- ex - life expectancy at age x.
Median age
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.
Natural increase
The number of births minus the number of deaths.
Overseas migration
Overseas migration is the movement of people in and out of Australia for the purpose of changing their country of usual residence. Overseas migrant arrivals are incoming travellers who are not currently counted in the population and who stay in Australia for 12 months or more over a 16-month period, and are then added to the population. Overseas migrant departures are outgoing travellers who are currently counted in the population and who leave Australia for 12 months or more over a 16-month period, and are then subtracted from the population. Net overseas migration is the difference between arrivals and departures and can be either positive or negative.
Population growth
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.
Population growth rate
Population change over a period as a proportion (percentage) of the population at the beginning of the period.
Population projections
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.
Replacement fertility
Replacement level fertility is the number of babies a female would need to have over her reproductive life span to replace herself and her partner. Given the current mortality of females up to age 49 years, replacement fertility is estimated at 2.1 babies per female.
Rest of state
Within each state and territory, except for the ACT, the area not defined as being part of the Greater Capital City Statistical Area is called the Rest of state region.
Sex ratio
The sex ratio relates to the number of males per 100 females. The sex ratio is defined for total population, at birth, at death and among age groups by appropriately selecting the numerator and denominator of the ratio.
Standardised death rate
Standardised death rates (SDR) 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:
- 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
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
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
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.
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