EXPLANATORY NOTES
INTRODUCTION
1 This publication contains statistics relating to overseas migration, interstate migration and the estimated resident population (ERP) by country of birth. It includes the number of settler arrivals by visa eligibility category as well as contextual information such as international migration statistics of other countries.
ESTIMATED RESIDENT POPULATION
2 Australia's population estimates for the period since 1971 are compiled according to the place of usual residence of the population. An explanation of the conceptual basis for population estimates is given in Information Paper: Demographic Estimates and Projections: Concepts, Sources and Methods (cat. no. 3228.0).
Status of quarterly ERP data
3 The status of quarterly ERP data changes over time from preliminary to revised to final. The following table shows the current status of ERP and the components of population change: natural increase, net overseas migration (NOM) and net interstate migration (NIM).
Method of estimation
4 The estimated resident population is an estimate of the Australian population obtained by adding to the estimated population at the beginning of each period the component of natural increase (on a usual residence basis) and the component of 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 Census counts by place of usual residence, to which are added the estimated Census net undercount and 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.
5 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 30 June dates in the respective Census years.
Birthplace
6 Estimated resident population by age and sex is calculated by country of birth for 30 June of each year by taking into account births, deaths and NOM over the preceding 12 months. All births in this period are added to the Australia-born population. Deaths during the period are subtracted from the population of the preceding year on the basis of financial year of birth, sex and country of birth. NOM is added to that population on the same basis.
NET OVERSEAS MIGRATION
7 Conceptually net overseas migration (NOM) is based on an international travellers' duration of stay being in or out of Australia for 12 months or more. It is 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). For the method based on the 12/16 rule this 12 months does not have to be continuous and is measured over a 16 month reference period. For example whether a traveller is in or out of the population is determined by their exact duration of stay in Australia over the subsequent 16 months after arrival or departure.
Source of overseas migration data
8 Estimates of NOM are calculated using administrative data collected and compiled by the Department of Immigration and Citizenship (DIAC) under the authority of the Migration Regulations (Migration Act, 1958). At present, the main source of data on overseas migration is the incoming and outgoing passenger cards completed by all persons arriving in or departing from Australia. Data from passports and visa (entry permit) applications and approvals are also provided by DIAC's Travel and Immigration Processing System (TRIPS). These three data sources are collected, compiled and matched together by DIAC.
9 Formerly DIAC was the Department of Immigration and Multicultural Affairs (DIMA) and the Department of Immigration and Multicultural and Indigenous Affairs (DIMIA).
10 Monthly extracts from files of matched passenger cards and TRIPS records are also the source for ABS Overseas Arrivals and Departures (OAD) statistics. OAD statistics are published on a monthly basis in Overseas Arrivals and Departures, Australia (cat. no. 3401.0).
CHANGE OF METHODS USED
11 The ABS has developed improved methods for estimating NOM. This has been used in estimating Australia's official population since September quarter 2006. Estimates of NOM based on the previous methods and those based on the improved methods are not comparable. The key change is the introduction of a '12/16 month rule' for determining a person's residency in Australia, replacing the previous '12/12 month rule'. Estimates of NOM up to June quarter 2006, use the previous methods for estimating NOM (12/12 rule) unless specified as using the improved methodology for earlier periods.
ESTIMATING NOM WITH THE 12/16 RULE
12 The method for estimating NOM has been reviewed in response to issues arising with the previous estimation of category jumping. The review also addressed the changing patterns of travel into and out of Australia, in particular the increased propensity for travellers to interrupt longer periods of stay or absence with short-term trips.
13 This improved NOM estimation methods employ a 12/16 rule where the traveller can be added or subtracted from NOM if they have stayed in or been absent from Australia for a period of 12 months or more over a 16 month period. This 12 months does not have to be continuous. Although a traveller states their intended duration of stay on a passenger card, for NOM purposes the ABS now records an individuals' actual travel behaviour.
Final NOM estimates
14 It is with the final NOM estimates that the 12/16 month rule can be fully applied. A traveller's actual duration of stay can only be calculated when data on overseas movements becomes available for the 16 months following a reference period. Final NOM estimation methods use ERP flags to determine if a traveller, through their actual duration of stay in or out of Australia, should be included or excluded from NOM estimates and consequently ERP estimates.
Preliminary NOM estimates
15 Preliminary NOM estimates contribute to ERP data which the ABS is legally obliged to produce each quarter. As the improved methods require 16 months of data to calculate actual duration of stay in or out of Australia, preliminary NOM estimates are therefore modelled on patterns of traveller behaviours observed in final NOM estimates for the same period two years earlier. Migration adjustments are then applied to account for differences between their intended duration of stay and their actual duration of stay. These migration adjustments are applied to travellers who are grouped according to age, sex, country of citizenship and state. They are calculated from changes in behaviour from final estimates two years earlier for the same groups of travellers.
16 Preliminary estimates using the improved method for estimating NOM were implemented in official ABS population estimates for September quarter 2006 and onwards with the release of the December quarter 2006 issue of Australian Demographic Statistics (cat. no. 3101.0).
17 For general information on the new improved method see Chapter 3: Net Overseas Migration in this publication. For more detailed information on the improved NOM estimation methods see Information Paper: Statistical Implications of Improved Methods for Estimating Net Overseas Migration, Australia, 2007 (cat. no. 3107.0.55.005) and Information Paper: Improved Methods for Estimating Net Overseas Migration, Australia, 2006 (cat. no. 3107.0.55.003).
ESTIMATING NOM WITH THE 12/12 RULE
18 Prior to 1 July 2006, NOM estimation methods used a 12/12 rule to determine if a traveller contributed to ERP. This meant that in order for a person to contribute to NOM they must stay in or be absent from Australia for a continuous period of 12 out of 12 months. It compared data on actual travel movements over a 12 month period with data on individual travellers' duration of stay as recorded on their passenger cards. In order to conduct such a comparison, data for a 15 month period (i.e. one year plus one quarter) were required. For more detail see Demography Working Paper 2003/5 - Net Overseas Migration: Adjusting for Actual Duration of Stay or Absence (cat. no. 3137.0).
Category jumping
19 Many overseas travellers stay (or are away) shorter or longer periods than initially intended, as recorded on their passenger cards (See Appendix 1: Passenger Cards). From July 1982 to June 1997, NOM estimates included an adjustment for the net effect of category jumping. Category jumping is a measure of the discrepancy between movements recorded as short-term, long-term or permanent at the time of movement, and the category recorded at the completion of a journey. Twelve months after a reference period it was determined whether the number of initially-recorded short-term, long-term and permanent arrivals and departures match actual patterns of movement.
20 For example, some visitors on arrival may state that they intend to stay in Australia for more than twelve months. However, they may change their travel plans and depart the country after only six months. Since migration figures are affected by this change in travel behaviour, an adjustment is incorporated into the NOM estimate and ERP.
21 The method used to estimate category jumping up until June 1997 inclusive was based on aggregate flows of traveller movements rather than individual travellers. Until June 1998 the measurement of duration of stay or absence on the second leg of travel was based on passenger reporting on the arrival or departure card. This self reported duration was used to determine the time at which a person arrived (for visitors) or left Australia (for Australian residents). However, from July 1998 onwards, implementation of a new passenger card design and processing system enabled DIMA (now DIAC) to derive actual duration of stay or absence by matching both arrival and departure cards rather than relying on passengers reporting their duration of stay or absence.
Matching traveller movements
22 Despite this improvement in the quality of actual duration of stay or absence data, the above estimation method appeared incapable of producing acceptable estimates of category jumping. Given that category jumping had only a small effect on ERP and that estimates produced by the above method seemed highly volatile, the ABS decided to set category jumping estimates to zero from September quarter 1997 onwards until an improved estimation technique was developed.
23 Through the provision of additional data from DIAC, the ABS now has the ability to match traveller movements over time. This enables a movement history to be constructed for those arriving and departing and thus calculate an actual duration of stay.
24 Matching traveller movements has enabled the adjustment of permanent and long-term movement. This adjustment (termed 'migration adjustment') allows for components of NOM to be presented on an adjusted basis.
ADJUSTMENT AND REVISION STATUS
25 Due to changes in the methods used to adjust NOM estimates, caution should be used comparing estimates over time. The table below describes the adjustment methods that have been applied to NOM estimates from September quarter 1996 and onwards.
26 For more information on category jumping and the interim methods of adjusting NOM for the previous (12/12) method, see Demography Working Paper 2003/5 - Net Overseas Migration: Adjusting for Actual Duration of Stay or Absence (cat. no. 3137.0). Adjustments applied to overseas migration estimates have also been discussed in a special article in Migration, Australia, 2002-03 (cat. no. 3412.0).
PERMANENT RESIDENCY GRANTS
27 A number of people arriving temporarily in Australia are subsequently granted permanent residency. These permanent residency grants contribute to the Australian Government's immigration targets but may be unrelated to the stated intentions of travellers on arrival. Accordingly, they are not included in unadjusted permanent arrivals in this publication, as they did not arrive in Australia on a permanent basis. The proportions of short-term and long-term visitor arrivals subsequently gaining on-shore grants of permanent residency are not routinely estimated in ABS statistics.
28 For more information on permanent additions to the population see the DIAC publication Immigration Update, available on the DIAC web site, <http://www.immi.gov.au>.
NET INTERSTATE MIGRATION
29 Interstate migration is a key determinant of the accuracy of state and territory population estimates. Data on interstate migration can not be directly estimated. Instead, post-censal estimates of interstate migration are modelled using administrative by-product data. Currently the data used by the ABS is information on interstate changes of address advised to Medicare Australia and to the Department of Defence in the case of the military. The Medicare-based model used for generating post-censal estimates of interstate migration is largely superseded when new Census information becomes available.
30 When Census data on interstate movement becomes available part of the process of rebasing ERPs for states and territories is the re-derivation of interstate migration for the intercensal period. The overall approach is to minimise state intercensal error using data analysed from the Census questions concerning an individual's place of residence one-year ago, five-years ago and at Census night. When new Census data are available, interstate migration estimates for the intercensal period are replaced with estimates derived from Census data on place of usual residence five years ago. These estimates are then scaled so that they sum to zero at the Australian level. A similar process is carried out for the year prior to the Census, using Census data on place of usual residence one year ago. The difference between the original interstate migration estimates and the rebased estimates is apportioned across all quarters, movement categories, ages and sex categories in the intercensal period in order to minimise quarterly change.
31 Due to the non-compulsory and non-universal nature of the available (indirect) data sources, post-censal quarterly estimates of interstate migration have long been considered the weakest measure of a component of population change. For further information on the process of estimating interstate migration and the administrative data used, see the Demography Working Paper: 2004/1 Review of Interstate Migration Method (cat. no. 3106.0.55.001) and the Information Paper: Evaluation of Administrative Data Sources for Use in Quarterly Estimation of Interstate Migration, 2006 to 2011 (cat. no. 3127.0.55.001).
Defence force adjustment
32 Medicare theoretically covers all Australian usual residents as well as those non-Australian residents granted temporary registration. However, there are a range of Australian usual residents who do not access the Medicare system, primarily due to access to alternative health services. One group is the military. As such, estimates of interstate migration produced from the interstate migration model described in the working paper Demography Working Paper: 2004/1 Review of Interstate Migration Method (cat. no. 3106.0.55.001) are adjusted to compensate for defence force movements not covered by Medicare. These adjustments are estimated using counts of defence force personnel by age, sex and state/territory, obtained from the Department of Defence, with 70% of any change in quarterly defence numbers assumed to be due to interstate migration not otherwise covered by the model.
OVERSEAS ARRIVALS AND DEPARTURES
33 Persons arriving in, or departing from, Australia provide information in the form of incoming and outgoing passenger cards (see Appendix 1). Incoming persons also provide information in visa applications (apart from people travelling as Australian or New Zealand (NZ) citizens). These and other information available to the Department of Immigration and Citizenship (DIAC) serve as a source for statistics of overseas arrivals and departures (OAD).
34 In July 1998, DIAC revised the incoming and outgoing passenger cards and associated procedures as well as computer systems. Following these changes, some questions on the passenger cards were not compulsory and answers to these questions were not checked by Customs officers. The question on marital status was deleted. Data on marital status is now derived from visa applications (only for certain visa classes) and is therefore not available for Australian or NZ citizens. The changes also affect the data for 'previous country of residence' which is imputed for Australian and NZ citizens. For more information see the May 1998 issue of Overseas Arrivals and Departures, Australia (cat. no. 3401.0). Since July 1998, there have been additional minor changes to both incoming and outgoing passenger cards.
35 From July 2001, DIAC adopted a new passenger card processing system which involved electronic imaging of passenger cards and intelligent character recognition of the data stored in the images. This process has yielded several improvements to the processing of passenger card data, most notably the detailed information about missing values. There have also been several changes to data quality. Further information on these changes is provided in Overseas Arrivals and Departures, Australia (cat. no. 3401.0).
Scope
36 Overseas arrivals and departures statistics relate to the number of movements of travellers rather than the number of travellers (i.e. multiple movements of individual persons during a given reference period are each counted separately). The statistics exclude the movements of operational air and ships' crew, of transit passengers who pass through Australia but are not cleared for entry, and of passengers on pleasure cruises commencing and finishing in Australia. Similarly, these statistics exclude unauthorised arrivals. For more information see Overseas Arrivals and Departures, Australia (cat. no. 3401.0).
Country of birth for New Zealand passport holders
37 With the introduction of biometric passports for NZ passports the country of birth of the holder no longer appears on the passport. This was the only source of information on the country of birth of NZ citizens travelling to or from Australia. Therefore, with the increased numbers of travellers holding NZ biometric passports the proportion of movement records with not stated country of birth increased substantially. For other travellers who are not NZ citizens, country of birth information can be obtained from their visa information. Visa information for most NZ citizens is not available as, under the trans-Tasman agreement, they do not need to hold a visa to travel to Australia. For August 2007 data, the total number of not stated responses for country of birth as supplied by DIAC was 76,763. NZ passport holders represented approximately 88% of these non-responses.
38 In order to alleviate this issue the records with not stated responses for country of birth have been imputed at the category of traveller and country of citizenship level from August 2007. As a result, the total number of not stated responses for country of birth has been reduced to 606 and the number of non-responses for NZ citizens to zero. This method of imputation will be in place until a more suitable means of obtaining or imputing country of birth data for NZ citizens can be implemented.
COUNTRY CLASSIFICATION
39 The classification of countries in this publication is the Standard Australian Classification of Countries. For more detailed information refer to the ABS publication Standard Australian Classification of Countries (SACC) (cat. no. 1269.0). This replaced the Australian Standard Classification of Countries for Social Statistics (ASCCSS) used in earlier issues of this publication.
40 The statistics on country of birth, citizenship, residence or main destination have certain limitations because of reporting on passenger cards. For instance, the United Kingdom includes England, Scotland, Wales, Northern Ireland, the Channel Islands and the Isle of Man. Similarly the United States of America includes 'America (undefined)'.
STATE AND TERRITORY CLASSIFICATION
41 Following the 1992 amendments to the Acts Interpretation Act to include the Indian Ocean Territories of Christmas Island and the Cocos (Keeling) Islands as part of geographic Australia, population estimates commencing from September quarter 1993 include estimates for these two territories. To reflect this change, another category of the state and territory level has been created, known as Other Territories. Other Territories include Jervis Bay Territory (previously included with the Australian Capital Territory), as well as Christmas Island and the Cocos (Keeling) Islands which were previously excluded from population estimates for Australia.
RELATED PUBLICATIONS
42 Recent publications released by the National Migrant Statistics Unit (ABS) include:
43 Other ABS products which may be of interest to users include:
44 Related statistics are also published by DIAC, available on the department's web site <
http://www.immi.gov.au>:
- Immigration Update;
- Population Flows - Immigration Aspects; and
- Settler Arrivals.
45 As well as the statistics included in this and related publications, additional demographic information is available on the ABS web site, <
https://www.abs.gov.au>; click Themes, then under People click on Demography. Users can also access the full range of electronic ABS data free of charge on the ABS web site.
ADDITIONAL STATISTICS AVAILABLE
46 The ABS may have other relevant data available on request. Generally, a charge is made for providing this information. Inquiries should be made to the National Information and Referral Service on 1300 135 070.
47 The following variables are available for overseas arrival and departure data:
- Age
- Airport/port of arrival/departure
- Arrival/departure date
- Australian residents:
- Country spent/intend to spend most time abroad
- Intended/actual time away from Australia
- Main reason for journey
- State or territory of intended address/state or territory of residence
- Category of travel
- Citizenship (nationality)
- Country of birth
- Country of embarkation/disembarkation
- Intention to live in Australia for next 12 months (not available for short-term movements)
- Marital status (not available for Australian and New Zealand citizens)
- Occupation (not available for short-term movements)
- Overseas visitors:
- Country of residence
- Intended/actual length of stay
- Main reason for journey
- State or territory of intended address/in which most time was spent
- Permanent migrants:
- Previous/future country of residence
- State or territory of intended address/lived
- Sex
48 The following variables are available for ERP by country of birth:
- Age: five-year age groups
- Country of birth
- Sex
- State/territory of usual residence: Census years only
49 Statistics of overseas arrivals and departures and related data are also published regularly by DIAC (see the Department’s quarterly publication,
Immigration Update) and by the Tourism Research Australia (on international travel and tourism).
ACKNOWLEDGMENTS
50 This publication draws extensively on information provided by DIAC. The ABS also uses 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.
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