Australian Bureau of Statistics
3228.0.55.001 - Population Estimates: Concepts, Sources and Methods, 2009
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 12/06/2009
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BIRTHS AND DEATHS
9.39 The ABS only collects a subset of data items from the registration process. Only data items which are required for statistical purposes are forwarded to the ABS by the RBDM.
Preliminary, revised and final estimates
9.40 There are three stages in the production of birth and death estimates for the purpose of compiling population estimates. These result in the production of preliminary, revised and final figures, based on the amount and type of data available at the time the estimates are produced.
9.41 Preliminary population estimates are used for a wide variety of purposes, including the distribution of government funds and services and the determination of each state and territories' number of seats in the House of Representatives (see Chapter 1 - Overview). Due to the importance of these estimates, it is vital that preliminary estimates of all components of population growth produced using limited data (including births and deaths), be as close as possible to those which will be produced at a later date using more complete data.
9.42 Conceptually, estimates of births and deaths used in quarterly post-censal population estimates should relate to the numbers of births and deaths occurring in each particular quarter. However, at the time preliminary population estimates are required (5 to 6 months after the end of each quarter), data to produce occurrence-based estimates are incomplete. Instead, the ABS uses data received from Registrars relating to the numbers of births and deaths registered in a quarter as a proxy for the number of occurrences. These preliminary estimates of births and deaths are based on 'raw' (i.e. unadjusted) counts of registrations for each quarter.
9.43 Preliminary estimates of births and deaths are revised using occurrence data 21 months after the end of each financial year, with adjustments applied to these occurrence-based estimates to reflect known trends in the delay in registration of births and deaths. These adjustments are termed 'inflation factors'. Further information on how these inflation factors are calculated is provided in Chapter 5 - Estimating births and deaths. Revised estimates are released in each September quarter issue of Australian Demographic Statistics (cat. no. 3101.0). For example, revised estimates of births and deaths for the 2006-07 financial year would be released in the September quarter 2008 issue of Australian Demographic Statistics (cat. no. 3101.0).
9.44 Estimates of births and deaths for each intercensal period are finalised after the following five-yearly Census of Population and Housing, based on the latest available occurrence data.
9.45 Information on births and deaths are obtained from a complete enumeration of births and deaths registered during a specified period and are not subject to sampling error. However they are subject to non-sampling error which can arise from inaccuracies in collecting, recording and processing of data. Every effort is made to minimise error by working closely with data providers, the careful design of forms, training of processing staff and efficient data processing procedures.
9.46 Sources of non-sampling error include:
9.47 The quality of preliminary births and deaths data, as measured by the differences between preliminary and revised estimates, are affected by delays between the occurrence of these events and their registration. These can be caused by a range of factors, and could include:
9.48 Preliminary estimates can also be subject to sudden 'shocks', e.g. processing lags due to peak workloads, holiday periods, or technical issues.
9.49 The delays (or lags) in registration are a greater problem for births than for deaths and are the main cause of differences between preliminary and revised estimates of natural increase. More information on these lags, and how adjustments are made to compensate for them, is provided in Chapter 5 - Estimating births and deaths.
Indigenous births and deaths
9.50 Although it is considered likely that most Aboriginal and/or Torres Strait Islander (Indigenous) births and deaths are registered, a proportion of these are not registered as being of Indigenous origin. Birth registrations classify a birth as being of Indigenous origin where at least one parent identified themselves as being of Indigenous origin on the birth registration statement. Death registrations classify a death as being of Indigenous origin where the person completing the registration form (be it a relative or other person acquainted with the deceased, or by an official of the institution where the death occurred) identifies the deceased person as Indigenous.
9.51 There are several data collection forms (including birth and death registration forms) on which information on the Indigenous origin of the person in question is requested. Due to a number of factors, the results are not always consistent. The likelihood that a person will identify, or be identified, as Indigenous on a specific form is known as their propensity to identify as Indigenous.
9.52 Propensity to identify as Indigenous is determined by a range of factors, including:
9.53 The way in which a person identifies, or is identified as Indigenous on a specific form can also change over time (this change in propensity to identify as Indigenous is detailed further in Chapter 8 - Estimating the Indigenous population). Together with delays in registration and uncertainty in the first place, these can lead to unexpected changes in Indigenous statistics. Over-precise analysis of Indigenous deaths and mortality should be avoided.
9.54 By linking registered deaths to Census records, the Census Data Enhancement (CDE) project allowed calculation of the expected number of Indigenous deaths. The Indigenous deaths identification rate was then calculated by taking the ratio of the number of deaths reported as Indigenous in death registrations to the number of deaths expected to be recorded as Indigenous in Census using results from the CDE project. The Experimental Life Tables for Aboriginal and Torres Strait Islander Australians, 2005-2007 (cat. no. 3302.0.55.003) publication found that the Indigenous deaths identification rate for Australia in 2006-07 was quite high (around 92%).
9.55 See the Information Paper: Census Data Enhancement - Indigenous Mortality Quality Study, 2006-07 (cat. no. 4723.0) for more information on the CDE project.
This page last updated 11 June 2009
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