AUSTRALIAN BUREAU OF STATISTICS, CENSUS OF POPULATION AND HOUSING

INTRODUCTION

1 The Census of Population and Housing (the Census) is the largest statistical collection undertaken by the Australian Bureau of Statistics (ABS). Its objective is to count the number of people in Australia on Census night, identifying their key characteristics and those of the dwellings in which they live.

2 The Census is conducted under the authority of the Census and Statistics Act, 1905.

3 Census data are collected on the characteristics of persons, families and households. In this product, data are presented on the following areas:

• cultural diversity
• families
• migration

SCOPE

4 The 2006 Census of Population and Housing aims to count every person who spent Census Night, 8 August 2006, in Australia. This includes people in the six states and the territories. The external Territories of Christmas Island and Cocos (Keeling) Islands are also in scope of Census while the external territory of Norfolk Island, and minor islands such as Heard and McDonald Islands, are outside the scope of the Australian Census.

5 All occupied dwellings are counted in the Census with the exception of diplomatic dwellings. Unoccupied private dwellings are also counted with the exception of unoccupied dwellings in caravan parks, marinas and manufactured home estates, and units in accommodation for the retired or aged.

6 Excluded from scope are diplomats and their families, and visitors from overseas who are not required to undergo migration formalities, such as foreign crews on ships. Australian residents out of the country on Census night are also excluded from scope.

7 Population counts can be based on the person's place of enumeration or place of usual residence.

REFERENCE PERIOD

8 The Census is conducted every five years. The 2006 Census was enumerated on the night of 8 August 2006.

KEY DATA ITEMS

9 Standard classifications are used to code Census data including:

• Standard Australian Classification of Countries (SACC) (cat. no. 1269.0)
• Australian Standard Classification of Languages (ASCL) (cat. no. 1267.0)
• Australian Standard Classification of Education (ASCED) (cat. no. 1272.0)
• Australian Standard Classification of Religious Groups (ASCRG) (cat. no. 1266.0)

10 The following Census variables are used in this product:

11 Country of birth: A person's birthplace is coded according to the SACC.

12 Dwelling structure: A dwelling is a structure which is intended to have people live in it, and which is habitable on Census night. Categories used in this product include:

• Separate house: A house which stands alone on its own grounds separated from other dwellings by at least half a metre.
• Semi-detached, row or terrace house, townhouse, etc: These dwellings have their own private grounds and no other dwelling above or below them.
• Flat, unit or apartment: These dwellings do not have their own private grounds and usually share a common entrance foyer or stairwell.
• Other: Includes caravan, cabin, houseboat, improvised home, tent, sleepers out (e.g. sheds), and house or flat attached to a shop, office, etc.

13 Family: A family is defined by the ABS as two or more persons, one of whom is at least 15 years of age, who are related by blood, marriage (registered or de facto), adoption, step or fostering, and who are usually resident in the same household. Each separately identified couple relationship, lone parent-child relationship or other blood relationship forms the basis of a family. Some households contain more than one family.

14 Family with dependent children: Includes families with a child under 15 years and/or a child of 15-24 years of age who attends a secondary or tertiary educational institution as a full-time student.

15 Household: A group of two or more related or unrelated people who usually reside in the same dwelling, who regard themselves as a household, and who make a common provision for food or other essentials for living; or a person living in a dwelling who makes provision for his/her own food and other essentials for living without combining with any other person.

16 Household composition: Describes the type of household within a dwelling:

• Family household: Can contain non-family members (unrelated persons and visitors)
• Multiple family household: Contains more than one family. A maximum of three families can be coded to a household
• Lone person household: Any private dwelling in which there is only one usual resident at least 15 years of age
• Group household: Consists of two or more unrelated people where all persons are aged 15 years or over. There are no reported couple relationships, parent-child relationships, or other blood relationships in these households.

17 Language spoken at home: Persons were asked to indicate whether they speak a language other than English at home. Information was coded according to the ASCL. Only one language was coded for each person.

18 Place of enumeration: A count of every person who spent Census night in Australia, based on where he or she was counted (as opposed to their place of 'usual residence').

19 Religious affiliation: Answering the question on religious denomination is optional, as provided for in legislation. Responses are coded to the ASCRG.

20 Usual residence: Usual residence data provides information on the usually resident population of an area and on internal migration patterns at the State and regional levels. The 2006 Census asked three questions on usual residence: where the person usually lives; where the person usually lived one year ago; and where the person usually lived five years ago.

GEOGRAPHY

21 The 2006 Census was coded according to the Australian Standard Geographical Classification (ASGC) 2006 (cat. no. 1216.0). In this product data are presented for each Local Government Area in NSW.

COLLECTION METHODOLOGY

22 Development phase: Before one Census is complete, development work on the next Census begins. This includes consultation with Census users on content changes. Field testing of Census topics is conducted before each Census along with a dress rehearsal to test collection and processing procedures.

23 Frame: A collection district (CD) is the basic geographic unit of collection in the Census. A CD is generally a Census workload area that one Census collector can cover to deliver and collect forms in a specified period. On average there are about 200 dwellings per CD. However, urban CDs may contain more, and rural areas fewer, dwellings. Forms are delivered to, and collected from, private and non-private dwellings in Australia by Census collectors.

24 Collection: Data are collected via self-enumeration questionnaires. Census collectors deliver forms to each dwelling before Census day and each household is asked to fill in the details required on the form on Census night. Assistance is available from the collector and the Census Inquiry Service (which includes a telephone interpreter service). Collectors are required to collect forms after Census night and visually scan each form to ensure it has been completed. If a respondent refuses to complete the form either a follow up letter is sent or the Area Supervisor attempts to convince the respondent to comply. Some cases may progress to a Notice of Direction and subsequent prosecution if the notice is not complied with.

25 Processing: For the 2006 Census, Intelligent Character Recognition (ICR) was used to capture the data from Census forms together with the use of automatic coding (AC) and computer assisted coding (CAC) in the processing phase.

26 A Data Processing Centre (DPC) was established to undertake the processing of data as follows:

• receipt and register of forms - a check was undertaken to ensure that all completed Census forms were received at the DPC
• data capture - the responses to the questions on the forms were coded automatically, or where this was not possible, semi-automatically
• editing - editing was undertaken to reduce the inconsistencies in Census data
• imputation - missing responses for sex, age, marital status and usual residence were imputed
• quality assurance - processes were implemented at the DPC to maximise the accurate and consistent recording of information from the Census forms.

ACCURACY

27 Since the 1966 Census, each Census has been followed by a Post Enumeration Survey (PES). The Post Enumeration Survey (PES) is used to determine how many people were missed in the Census and how many were counted more than once. It is a household survey conducted by ABS interviewers shortly after the Census. The survey provides an independent check on Census coverage and also identifies the key demographic characteristics of the population that have been missed or over counted in the Census. The 2006 Census has a net undercount rate of 2.7%, which is higher than that for the 2001 Census (1.8%).

28 Census data are subject to errors by respondents or mistakes in collection or processing. The main kinds of error are as follows:

• miscounting - although the Census aims to count each person, some people are missed or counted more than once
• partial non-response - people who are included in the Census do not always answer all the questions which apply to them
• respondent error - editing procedures are used to detect and correct obvious errors made by individuals completing the Census form (e.g. a six year old in the labour force). However, not all errors can be detected in the editing process and some remain in the final data
• processing error - errors which may occur during the processing of the Census are minimised by means of quality assurance procedures
• random adjustment - cells containing small values are randomly adjusted or suppressed to avoid releasing information about particular individuals, families or households.

29 When Census data are tabulated, cells containing small values are randomly adjusted or suppressed to avoid release information about particular individuals, families or households. The effect of random adjustment is statistically insignificant.

COLLECTION HISTORY

30 New South Wales was the first colony to conduct a Census in 1828. Prior to this population counts were known as musters. Each of the colonies conducted its own Census until 1886. While the first simultaneous Census of all Australian colonies occurred in 1881, the first national Census was taken in 1911. It was followed by others in 1921, 1933, 1947 and 1954. Since 1961, Censuses have been conducted regularly every five years (1966, 1971, 1976, 1981, 1986, 1991, 1996, 2001 and 2006).

31 Some topics have remained constant over time such as age, marital status and religion. Other topics have been included and excluded at different Censuses (for further information see Metadata).

METADATA

32 Further information about the Census is available from the ABS in publications such as How Australia Takes a Census (cat no. 2903.0), the Census Dictionary (cat. no. 2901.0) and the Information Paper: 2006 Census of Population and Housing, Nature and Content (cat. no. 2008.0).

PUBLISHED DATA

33 For further information about published Census data, see the ABS Catalogue of Publications and Products (cat. no. 1101.0) or visit the ABS web site.

ABS DATA AVAILABLE ON REQUEST

34 As well as the statistics included in this and related publications, the ABS may have other relevant data available on request. For further information, please contact the National Information and Referral Service on 1300 135 070.