Introduction
1 This publication contains three series of population projections for Tasmania by Statistical Division (SD) and major urban areas for the period 30 June 1999 to 30 June 2021 and by Statistical Subdivision (SSD) and Statistical Local Area (SLA) for the period 1999 to 2006, 2011, 2016 and 2021. Population projections by age and sex are also included for Tasmania and all SLAs and LGAs for the period 1999 to 2006, 2011, 2016 and 2021.
2 Additional data relating to this series of projections, including population by sex and single years of age, can be obtained by contacting the ABS Information Service.
Objectives
3 The Australian Bureau of Statistics (ABS) has published three series of population projections for Tasmania and lower geographical levels in Tasmania to service the needs of users of population projections.
4 The projection results published by the ABS are not intended as predictions or forecasts, but are illustrations of growth and change in the population which would occur if the assumptions about future demographic trends prevail over the projection period.
5 While the assumptions for the projections are formulated on the basis of an assessment of past demographic trends, both in Australia and overseas, there is no certainty that any of the assumptions will or will not be realised. In addition, no assessment has been made of changes in non-demographic conditions such as major government policy decisions and economic factors which may affect future demographic behaviour.
6 Accordingly, three projection series have been provided in recognition of this uncertainty and to provide users with a range of options.
Development
7 The process of developing population projections involves research, analysis, consultation and computation. Analysis of demographic trends, research into the determinants of population growth and distribution, and consultation with government at both national and State levels are necessary to formulate the various assumptions and to ensure their general relevance for the projection period.
8 Consultation has been ongoing with the Tasmanian Government. Assumptions initially specified in a Memorandum of Understanding were refined and finalised for the three series of population projections. One assumption was used for fertility, mortality and overseas migration and three assumptions were used for internal migration.
9 There are many techniques which may be used for population projections, ranging from simple extrapolations through broad economic, social and time-series analysis to detailed component methods. The ABS uses the cohort-component method, which begins with a base population for each sex by single years of age and advances it year by year by applying assumptions regarding future mortality and migration. Assumed age-specific fertility rates are applied to the female populations of child-bearing ages to provide the new cohort of births. This procedure is repeated for each year in the projection period for Tasmania. It is also repeated to obtain projections by Statistical Division and capital city/balance for Tasmania, while constraining annually by age and sex to the Tasmanian projections. The technique was also used for population projections at the Statistical Local Area level, with the assumptions taking into account major economic activities that are likely to impact on the population of SLAs in the next 10 years.
10 Projections of SLAs with very small populations often significantly diverge from what the future actually holds. The cohort-component projection method employed uses the population by single year of age and sex, but when most of the cells are between 0 and 2 the generation of robust assumptions and a plausible age/sex projection is extremely difficult. Accordingly, the SLAs of Hobart Inner and Launceston Inner were held constant for the duration of the projection period.
Assumptions
Fertility
11 Single year age-specific fertility rates for Tasmania were calculated by applying the 1996-1998 ratios of Tasmania to Australian age-specific fertility to the low Australian fertility assumption. This assumption assumes fertility declines to 1.67 babies per woman by 2007-08 for Tasmanian mothers and then remains constant to the end of the projection period.
12 Age-specific fertility rates for Hobart capital city and the balance of Tasmania were calculated by applying fertility differentials for each single year of age to the assumed age-specific fertility rate for Tasmania for each year in the projection period. Fertility differentials for Hobart capital city and the balance of Tasmania were assumed to be the average differential of the years 1996-1998.
13 Fertility assumptions for SLAs were based on average age-specific fertility rates observed in each SLA between 1995 and 1999, projected to follow the assumed changes at the Tasmanian level until 2008 and then remain constant to 2021.
Mortality
14 Projected life expectancy at birth was based on the Australian trend in life expectancy at birth using five yearly intervals between 1985-1987 and 1995-1997 (centring on the population census years). From 1996-1998, male and female life expectancies for Australia were projected to increase by 0.30 and 0.22 years respectively, each year until 2001-2003, thereafter, life expectancy was assumed to increase at a diminishing rate.
15 The pattern of decline in age-sex-specific death rates from 1970-1972 to 1995-1997 was assumed to continue from 1999 to 2021, within the constraints of the predetermined levels of life expectancy at birth. Where there was an upward trend in age-sex-specific death rates, some limitations were applied to prevent an increase in assumed future mortality rates for particular ages.
16 The mortality assumptions for Hobart capital city and the balance of Tasmania were based on the age-specific assumptions for Tasmania, adjusted for differences in historical life expectancy. The percentage differentials in life expectancy between Hobart capital city and the balance of Tasmania prevailing in 1996-1998 were maintained throughout the projection period.
17 The mortality assumptions for SLAs were based on the age-specific assumed mortality rates for Tasmania, adjusted across all ages to provide consistency with the overall mortality experienced in each SLA between 1995 and 1999.
Overseas migration
18 Tasmania's average share of Australia's net overseas migration for the three-year period 1996-97 to 1998-99 was used as the basis for calculating the share going to Tasmania during the projection period.
19 Net overseas migration to Tasmania was divided between the Hobart capital city and the balance of Tasmania based on the proportion of recent arrivals recorded in the 1991 and 1996 Censuses. The average of these two censuses was used to divide net overseas migration into overseas migration by Statistical Division.
20 The assumed age-sex structure of each overseas migration component for Tasmania was based on the average structure from 1996-97 to 1998-99. This varies during the projection period because the relative contribution of permanent and long-term components changes as long-term arrivals and departures increase from year to year. Age-sex profiles at the part of Tasmania level were derived from the 1996 Census question on residence one year ago. Overseas departures are assumed to have much the same age-sex distribution as overseas arrivals. These distributions were constrained to Tasmanian overseas arrivals and departures data for 1995-96. Age-sex profiles for category jumping are assumed to be the same as for permanent arrivals.
Internal migration
21 The long-term average net interstate migration experience of Tasmania was used as the basis for the medium assumption for Tasmania, with more weight given to the past 10 years.The high and low assumptions reflect the volatility in Tasmania's interstate migration data and give a plausible broad range of projection outcomes, particularly in the short term.
22 Net internal migration to Hobart capital city and the balance of Tasmania was based on historical trends. Historical net total migration was assumed to be the difference between population growth and natural increase. Net internal migration was assumed to be the difference between net total migration and net overseas migration.
23 Assumed age-sex profiles of future internal flows were derived from the 1996 Census distribution of internal movements in 1995-96, constrained to estimates for internal migration in 1995-96. Profiles for arrivals and departures were generated separately. Age-sex profiles were assumed to remain unchanged throughout the projection period.
Geographic Boundaries
24 This publication contains data presented according to the geographic boundaries defined in Australian Standard Geographical Classification (ASGC) 2000 (Cat. no. 1216.0).
25 Maps have been included on pages 99 and 100. However, a map showing all Statistical Local Areas for Tasmania has not. A copy is available from any ABS office or on the ABS Website and accessing Statistics/Statistical Concepts Library/ABS Classifications.
Acknowledgment
26 ABS publications draw extensively on information provided freely by individuals, businesses, governments and other organisations. Their continued cooperation is very much appreciated: without it, the wide range of statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.
Related Publications and References
27 Users may also wish to refer to the following ABS publications:
- Australian Demographic Statistics (Cat. no. 3101.0) - issued quarterly
- Australian Demographic Trends (Cat. no. 3102.0) - issued irregularly
- Births, Australia (Cat. no. 3301.0) - issued annually
- Causes of Death, Australia (Cat. no. 3303.0) - issued annually
- Deaths, Australia (Cat. no. 3302.0) - issued annually
- Demographic Estimates and Projections: Concepts, Sources and Methods, Statistical Concepts Library, ABS Website.
- Demography, Tasmania (Cat. no. 3311.6) - issued annually
- Experimental Projections of the Aboriginal and Torres Strait Islander Population (Cat. no. 3231.0) - issued irregularly
- Household and Family Projections, Australia, 1996 to 2021 (Cat. no. 3236.0) - issued irregularly
- Migration, Australia (Cat. no. 3412.0) - issued annually
- Overseas Arrivals and Departures, Australia (Cat. no. 3401.0) - issued monthly
- Population by Age and Sex, Australian States and Territories (Cat. no. 3201.0) - issued annually.
28 Current publications issued by the ABS are listed in the Catalogue of Publications and Products (Cat. no. 1101.0). The ABS also issues, on Tuesdays and Fridays, a Release Advice (Cat. no. 1105.0) which lists publications to be released in the next few days. The Catalogue and Release Advice are available from any ABS office or on the ABS Website.
29 As well as the statistics included in this and related publications, additional information is available from the ABS Website at and accessing Themes/Demography.
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