3201.0 - Population by Age and Sex, Australian States and Territories, Jun 1997 to Jun 2002  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 27/03/2003   
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Ageing of the population

Ageing of the population is the consideration of the proportion of the population aged 65 years and over, and the way this proportion is continuing to increase, mostly due to persistent low fertility rates and declining mortality rates.

Census count

The Census of Population and Housing enumerates persons on the basis of where they were located on census night. Characteristics of households are only available according to place of enumeration. The Census also compiles information on people according to their place of usual residence. This information is coded to Statistical Local Areas. This means that census counts of people can be produced according to their location on census night as well as their place of usual residence.

Estimated resident population

Estimated resident population (ERP) are estimates of the Australian population obtained by adding to the estimated population at the beginning of each period the components of natural increase (on a usual residence basis) and net overseas migration. For the states and territories, account is also taken of estimated interstate movements involving a change of usual residence.

Estimates of the resident population are based on adjusted (for underenumeration) census counts by place of usual residence, to which are added the number of Australian residents estimated to have been temporarily overseas at the time of the Census. Overseas visitors in Australia are excluded from this calculation.

After each census, estimates for the preceding intercensal period are revised by incorporating an additional adjustment (intercensal discrepancy) to ensure that the total intercensal increase agrees with the difference between the ERPs at the two respective census dates.

The concept of ERP links people to a place of usual residence within Australia. Usual residence is that place where each person has lived or intends to live for six months or more from the reference date for data collection.

Intercensal discrepancy

Intercensal discrepancy is the difference between two estimates of a census year population, the first based on the latest census and the second arrived at by updating 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.

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

Net overseas migration is net permanent and long-term overseas migration plus an adjustment for the effect of category jumping.

Mean age

The average age of the population.

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.

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.

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.