There is widespread interest in information about the size, composition and distribution of Australia's population and how these may change over time. Governments have an obvious interest because of their obligation to enhance the wellbeing of all citizens. Businesses and other organisations have interests in knowing the likely demand for the various goods and services they provide. A common concern for users of population statistics relates to the resource implications associated with meeting people's needs and how increasing demands for resources associated with population growth can be managed.
RECOGNITION BY GOVERNMENT
The notion of having a fair basis for political representation in our Houses of Parliament underpins our democracy and is part of the social compact that Australian citizens have with government. This compact, written into federal law as the Commonwealth Electoral Act 1918, determines that the number of representatives from each State (and Territory) to sit in the House of Representatives must be set relative to the number of people in each State (and Territory). As a consequence, up-to-date population estimates are needed to maintain the representation standards. Indeed, Federal legislation obliges the ABS to produce quarterly estimates of the population in each State and Territory (see Sub-section 9 of the Census and Statistics Act 1905).
Having a fair basis for allocating public expenditures is also of critical importance and demands the provision of up-to-date population statistics for areas administered by different levels of government. Population estimates are specifically used to help determine the annual allocation of Commonwealth funds for State governments (A new tax system (Commonwealth-State Financial Arrangements) Act 1994) and for local governments (Local Government (Financial Assistance) Act 1995).
SUSTAINABILITY OF A GROWING POPULATION
The growth of the world's human population and its increasing demand for limited global resources is a key issue for citizens and governments throughout the world. This is coupled with evidence that many of the life support systems that make-up our natural environment are being degraded by human activity and that continued population growth will add to the pressure experienced by these systems. These issues have come to be regarded as important no matter where people live, including countries with small populations, because all people influence, and ultimately depend on, the quality of the environment (its climate, soils, water, bio-diversity) for their wellbeing.
Of course, each place in the world also has its own unique set of issues related to population pressure. In Australia, these concerns have been expressed in periodic political debates about the optimal size of the population. Some of the major issues in these debates relate to Australia's poor endowment of fertile soils and the limited supply of fresh water over much of the landscape. Estimates of 'carrying capacity' have varied considerably, ranging from hundreds of millions to a population level lower than the current one.2 These variations depend on the criteria being used to define carrying capacity (ranging from food production to ecological degradation), the standard of living assumed, and on speculations that future technologies and other human endeavours may serve to extend the availability of resources. Because of the complexity of the issue and the diversity of views, no firm conclusions have been reached.
AGEING OF THE POPULATION
Of increasing concern is the change in the age profile of the population which has seen a falling proportion of younger people and a growing proportion of older people. Projections, based on past and expected future trends in fertility, mortality, and net migration, show that with all plausible assumptions these trends will continue. Comparisons with other countries show that the ageing trend is a common experience among similarly developed countries. The consequences of the changes are attracting increasing debate, with some scenarios suggesting a need for action to help maintain living standards. For example, because the later stages of life have been associated with low income and high demands for health and community care, the adequacy of government budgets (under established tax regimes) to support older people has become a major issue of concern. Pro-birth and pro-immigration policies have been considered as possibilities to reduce the ageing process. Other social responses to perceived fiscal problems from aged support programs have been to encourage people to provide for themselves in their retirement through compulsory superannuation and other saving strategies.
Despite ups and downs in numbers of migrants coming to Australia, the migration of people from other countries has long been supported and encouraged by Australian governments. Support for migration has generally been associated with the desire to attract skilled labour to help Australia's economic development and to increase the size of national markets but there have been other interests as well. For example, as made popular by the slogan 'populate or perish', migration was encouraged during the twentieth century to help secure Australia from threats of invasion. A feature of patterns of immigration to Australia over more recent decades has been the increasing diversity of countries of origin from which migrants have come. At the global level there have also been large increases in numbers of people seeking to move to more stable, well off countries, like Australia, because of economic and political difficulties in their own countries. Increases in levels of illegal immigrants have been one of the consequences of this trend.
There are a number of issues for which data that monitors the intake of migrants is important. One concerns the contribution of immigration to the overall size and structure of the population which, as previously discussed, relates to the debate on the sustainability of population growth. Another issue, often raised during periods of economic recession, relates to fears that immigration may set up extra competition for limited employment opportunities. Yet another concern relates to the diverse backgrounds from which people come. Cultural diversity is celebrated in Australia but, at the same time, is challenged by some groups who feel uncomfortable in sharing their future with people who have competing needs for limited resources, especially when some of those people have different looks, languages, beliefs and values. Statistical information that describes the flow of migration and its consequences for living standards is vital to informing public policy debates and shaping future immigration policies.
Monitoring trends in fertility is important because it is a major factor influencing rates of population growth and because it is the major factor affecting changes in the age composition of the population. In Australia, as in many other developed countries, there has been increasing interest in ways to arrest the on-going decline in fertility rates which have fallen to levels lower than that needed to replace the population and to family sizes lower than young women say they aspire to have.3 Information that contributes to our understanding of the biological, social and economic factors that influence the numbers of children born is needed to support possible public policy options.
Resources need to be available to people according to the places in which they live. For resources over which governments have responsibilities, such as roads, electric power, telecommunication, schools, hospitals, community service centres, and so on, information on population numbers is often vital to planning processes associated with the delivery and maintenance of such services. Businesses also have demands for such information in providing a wide range of goods and services. While population numbers are vital to planning processes so too is information about the relative wellbeing of people in those areas. More detailed information about the circumstances of people living in particular areas, their demographic composition, whether the population is growing or declining, whether the community is relatively affluent or not, helps with targeting and prioritising efforts to provide goods and services.
The issues associated with population size and composition differ according to places of interest, be they global, national, or local. Many issues associated with population pressure are most evident in cities which, by definition, refer to places with high concentrations of large numbers of people. As in many cities throughout the world the growth of Australia's cities has been associated with problems such as traffic congestion, urban sprawl, overcrowding, air and noise pollution, beach pollution from drainage runoffs and sewerage discharge, securing adequate supplies of water, and difficulties of waste disposal. Of course the solution to many of these problems may lie in better planning and regulation of the many human activities that contribute to such problems rather than controlling population size. Information that describes the numbers of people affected by various problems, and supports the analysis of whether growth is sustainable in terms of available infrastructures, is vital to considering various development strategies.