GLOSSARY

12/12 month rule

A method for measuring an overseas traveller's duration of stay or absence in which the 12 month usual residence criterion in population estimates is measured across a 12 month period. Under a 12/12 month rule, overseas travellers must be resident in Australia for a continuous 12 month period or more to be included in the estimated resident population. Similarly, Australian residents travelling overseas must be absent from Australia for a continuous 12 month period or more to be removed from the estimated resident population.

12/16 month rule

A method for measuring an overseas traveller's duration of stay or absence which takes an approach to measure usual residence that does not have to be continuous, as opposed to the continuous approach used under a 12/12 month rule. Under a 12/16 month rule, overseas travellers must have been resident in Australia for a total period of 12 months or more, during the 16 month follow-up period to be included in he estimated resident population.

The 12/16 month rule therefore 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.

Age-specific fertility rates

Age-specific fertility rates in this publication are the number of live births (occurred or registered) during the financial year, according to age of mother, per 1,000 of the female estimated resident population of the same age at 31 December. For calculating these rates, births to mothers under 15 years are included in the 15-19 years age group, and births to mothers aged 50 years and over are included in the 45-49 years age group. Pro rata adjustment is made in respect of births for which age of mother is not given.

Average annual rate of growth

The average annual growth rate, r, is calculated as a percentage using the formula:

r =

where P₀ 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 P₀ and P_n in years.

Average household size

Average household size refers to the number of persons per household in private dwellings.

Balance of state or territory

The aggregation of all Statistical Divisions (SD) within a state or territory other than its capital city SD (see Major Statistical Region in Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

Birth

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.

Capital city

Refers to the capital city Statistical Divisions of state and territories as defined in Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

Category of movement

Category of movement for overseas arrivals and departures is classified according to length of stay (in Australia or overseas), as recorded by travellers on passenger cards. There are three main categories of movement:

• permanent movements;
• long-term movements (one year or more); and
• short-term movements (less than one year).

A significant number of travellers (i.e. overseas visitors to Australia on arrival and Australian residents going abroad) state exactly 12 months or one year as their intended period of stay. Many of them stay for less than that period and on their departure from, or return to, Australia are therefore classified as short-term. Accordingly in an attempt to maintain consistency between arrivals and departures, movements of travellers who report their actual or intended period of stay as being one year exactly are randomly allocated to long-term or short-term, in proportion to the number of movements of travellers who report their actual length of stay as up to one month more, or one month less, than one year.

Census

The complete enumeration of a population or groups at a point in time with respect to well-defined characteristics (eg Population, Manufacturing, etc.). When the word is capitalised, "Census" usually refers to the national Census of Population and Housing.

Collection District (CD)

The smallest geographic area defined in the Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

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 conducted 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 or citizenship, 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. It excludes overseas visitors who are in Australia for less than 12 months.

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 occurring between t and t+1, represented by the following equation:

P_t+1 = P_t + B - D + NOM + NIM.

Household

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.

Household population

The household population is the estimated resident population (ERP) that usually lives in private dwellings. It is the ERP less the population that usually lives in non-private dwellings.

Infant death

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 discrepancy

Intercensal discrepancy is the difference between two estimates at 30 June of a Census year population: then first based on the latest Census, and the second arrived at by updating the 30 June estimate of the previous Census date estimate with intercensal components of population change which take account of information available from the latest Census. It is caused by errors 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.

Intercensal error

Intercensal error 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 which do not take account of information available from the latest Census.

Local Government Area (LGA)

LGA is a spatial unit which represents the whole geographical area of responsibility of an incorporated Local Government Council, an Aboriginal or Island Council in Queensland, or a Community Government Council (CGC) in the Northern Territory. An LGA consists of one or more SLAs. LGAs aggregate directly to form the incorporated areas of states/territories. The creation and delimitation of LGAs is the responsibility of the state and territory Governments. The number of LGAs, their names and their boundaries vary over time. Further information concerning LGAs is contained in Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

Long-term arrivals

Long-term arrivals comprise:

• overseas migrants (compromising visitors and temporaty entrants) who intend to stay in Australia for 12 months or more (but not permanently); and
• Australian residents returning after an absence of 12 months or more overseas.

Long-term departures

Long-term departures comprise:

• Australian residents who intend to stay abroad for 12 months or more (but not permanently); and
• overseas visitors departing who stayed 12 months or more in Australia.

Long-term departures comprise:

• Australian residents who intend to stay abroad for 12 months or more (but not permanently); and
• overseas visitors departing who stayed 12 months or more in Australia.

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.

Migration adjustment

Under the previous NOM method 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 comprise 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'.

Natural increase

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. It is:

• based on an international travellers' duration of stay being in or out of Australia for 12 months or more;
• the difference between the number of incoming travellers who stay in Australia for 12 months or more and are added to the population (NOM arrivals) and the number of outgoing travellers who leave Australia for 12 months or more and are subtracted from the population (NOM departures).

When using the current method for estimating final net overseas migration this term is then based on a travellers' actual duration of stay or absence using the 12/16 rule. Preliminary NOM estimates are modelled on patterns of traveller behaviours observed in final NOM estimates for the same period two years earlier.

NOM arrivals

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 and are added to the population.

When using the current method for estimating net overseas migration this term is then based on a travellers' actual duration of stay using the 12/16 rule.

NOM departures

NOM departures are all overseas departures that contribute to net overseas migration (NOM). It is the number of outgoing international travellers (Australian residents and long term visitors to Australia) who leave Australia for 12 months or more and are subtracted from the population.

When using the current method for estimating net overseas migration this term is then based on a travellers' actual duration of absence using the 12/16 rule.

Net permanent and long-term movement

Under the previous NOM method, the difference between the number of permanent (settler) and long-term arrivals and the number of permanent and long-term departures. Short-term movements are excluded.

Net undercount

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 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 resultant of Census undercount, overcount, misclassification and imputation error.

Overseas arrivals and departures (OAD)

Overseas arrivals and departures (OAD) refer to the arrival or departure of Australian residents or overseas visitors, through Australian airports (or sea ports), which have been recorded on incoming and outgoing passenger cards. Statistics on OAD relate to the number of movements of travellers rather than the number of travellers (i.e. the multiple movements of individual persons during a given reference period are all counted).

Permanent arrivals (settlers)

Permanent arrivals (settlers) comprise:

• travellers who hold migrant visas (regardless of stated intended period of stay);
• New Zealand citizens who indicate an intention to settle; and
• those who are otherwise eligible to settle (e.g. overseas born children of Australian citizens).

This definition of settlers is used by the Department of Immigration and Citizenship (DIAC). Prior to 1985 the definition of settlers used by the Australian Bureau of Statistics (ABS) was the stated intention of the traveller only. Numerically the effect of the change in definition is insignificant. The change was made to avoid the confusion caused by minor differences between data on settlers published separately by the ABS and the DIAC.

Permanent departures

Permanent departures are Australian residents (including former settlers) who on departure state that they are departing permanently.

Post enumeration survey

The Census Post Enumeration Survey (PES) is a household survey conducted three to four weeks after the Census. The PES allows the ABS to estimate the number of people missed in the Census and the number counted more than once. Usually more people are missed than 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.

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. After the census, intercensal population growth also includes an allowance for intercensal discrepancy.

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 overseas. 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.

Population projections are not predictions or forecasts. They are an assessment of what would happen, in future years, to Australia's population given a set of assumptions about future trends in fertility, mortality and migration.

Sex ratio

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.

Short-term arrivals

Short-term arrivals comprise:

• overseas visitors/migrants who intend to stay in Australia for less than 12 months; and
• Australian residents returning from overseas after an absence of less than 12 months.

Short-term departures

Short-term departures comprise:

• Australian residents who intend to stay abroad for less than 12 months; and
• overseas visitors departing after a stay of less than 12 months in Australia.

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 ABS standard populations relate to the years ending in 1 (e.g. 1991). The current standard population is all persons in the Australian population at June 2001. 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.

Wherever used, the definition adopted is indicated.

State or territory and Statistical Local Area of usual residence

State or territory and Statistical Local Area (SLA) of usual residence refers to the state or territory and SLA 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 settlers, and by Australian residents returning after a journey abroad. Particularly in the case of the former, this information does not necessarily relate to the state or territory in which the traveller will eventually establish a permanent residence.

Statistical District (S Dist)

Statistical Districts (S Dist) consist of selected, significant, predominantly urban areas in Australia which are not located within a Capital City Statistical Division (SD). S Dists enable comparable statistics to be produced about these selected urban areas. Further information concerning S Dists is contained in Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

Statistical Division (SD)

Statistical Divisions (SD) consist of one or more Statistical Subdivisions (SSD). These are designed to be relatively homogeneous regions characterised by identifiable social and economic units within the region, under the unifying influence of one or more major towns or cities. Information concerning SDs is contained in Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

Statistical Local Area (SLA)

Statistical Local Areas (SLA) are, in most cases, identical with, or have been formed from a division of, whole Local Government Areas (LGA). In other cases, they represent unincorporated areas. In aggregate, SLAs cover the whole of a state or territory without gaps or overlaps. In some cases legal LGAs overlap statistical subdivision boundaries and therefore comprise two or three SLAs (Part A, Part B and, if necessary, Part C). Further information concerning SLAs is contained in Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

Statistical Subdivision (SSD)

Statistical Subdivisions (SSD) are of intermediate size, between Statistical Local Areas (SLA) and Statistical Divisions (SD). In aggregate, they cover the whole of Australia without gaps or overlaps. They are defined as socially and economically homogeneous regions characterised by identifiable links between the inhabitants. In the non-urban areas an SSD is characterised by identifiable links between the economic units within the region, under the unifying influence of one or more major towns or cities. Further information concerning SSDs is contained in Statistical Geography: Volume 1 - Australian Standard Geographical Classification (ASGC) (cat. no. 1216.0).

Total fertility rate (TFR)

The sum of age-specific fertility rates (live births at each age of mother per female population of that age). 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.

Under enumeration

See net undercount.