Census in Australia
The Australian census is administered by the Australian Bureau of Statistics  every five years. The most recent census was conducted on August 8, 2006.  Prior to the introduction of regular censuses in 1961, they have also been run in 1901, 1911, 1921, 1933, 1947 and 1954. It is compulsory for all households to fill in all questions, except those relating to religion and the archiving of personal census details. The census counts all people who spend census night within Australia and its external and internal territories, with the exception of foreign diplomats and their families.
The Census and Statistics Act 1905 (Cwlth) led to the 1906 establishment of the Commonwealth Bureau of Census and Statistics (CBCS).  The Bureau was renamed as the Australian Bureau of Statistics in 1975.

# Australian Standard Geographical Classification
The census is collected and published against geographic areas defined by the Australian Standard Geographical Classification.  The smallest spatial unit used for collecting and recording Census data is the Census Collection District (CD).  It can be added up, or aggregated, to cover larger areas, like Statistical Local Areas (SLA's). The main ASGC hierarchy for the census includes the following geographic areas:
- Collection District (CD)
- Statistical Local Area (SLA)
- Statistical Subdivisions (SSD)
- Statistical Divisions (SD)
- States or Territories (S/T)
- Australia
The traditional concept of a Collection District is that it was the area that one Census collector can cover (delivering and collecting census forms) in about a ten-day period.  In the 2001 Census, Census collectors may be allocated more than one urban collection district because of their size. In urban areas collection districts average about 220 dwellings. In rural areas the number of dwellings per collection district reduces as population densities decrease.
For the 2001 Census there were 37,209 collection districts and 1,353 Statistical Local Areas defined throughout Australia.

# Privacy
The Census and Statistics Act 1905 and Privacy Act 1988 guarantee that no personally-identifiable information is released from the ABS to other government organisations, or the public. However the 2001 census offered for the first time, an option to have personal data archived by the National Archives of Australia and released to the public 99 years later and in 2001 54% of Australians agreed to do so. The ABS also makes confidentialised Census data available to researchers, who must make various legal commitments before being given access.
In the 1970s there was public debate about privacy and the census. In 1979 the  Law Reform Commission reported on Privacy and the Census. One of the key elements under question was the inclusion of names. It was found that excluding names reduced the accuracy of the data; individuals were more likely to leave questions blank and post-enumeration surveys would not be possible.

# Counting Indigenous Australians
In 1967, a referendum was held which approved two amendments to the Australian constitution relating to Indigenous Australians.  The second of the two amendments related to Section 127, which said: "In reckoning the numbers of the people of the Commonwealth, or of a State or other part of the Commonwealth, Aboriginal natives shall not be counted." The referendum deleted this section from the Constitution. It was widely believed at the time, and is still often said, that this was a reference to the census, and that Aboriginal people were not counted in Commonwealth censuses before 1967. In fact the section related to calculating the population of the states and territories for the purpose of allocating seats in Parliament and per capita Commonwealth grants. Its purpose was to prevent Queensland and Western Australia using their large Aboriginal populations to gain extra seats or extra funds. Aboriginal people living in settled areas were counted in censuses before 1967.
The first Commonwealth Statistician, George Handley Knibbs, obtained a legal opinion that persons of the half blood are not aboriginal natives for the purposes of the Constitution. The first Australian census in 1911 included in its population tables only those of half or lesser Aboriginal descent.

# Australian Standard Classification of Cultural and Ethnic Groups
Ancestry data was included in the 1986 census.  It was found when the data was evaluated that people who filled in the census were not sure what the question meant and there were inconsistent results, particularly for those people whose families had been in Australia for many generations. There were no ancestry related questions in 1991 or 1996.  For 2001 it was decided that development of Government policies did need information about people who were either born overseas, or whose parents were born overseas.  The questions were to mark the ancestries most closely identified with and to consider ancestry back as far as three generations. Respondents had the option of reporting more than one ancestry but only the first two ancestries they reported were coded for the Census.
The results for 2001 were coded using the Australian Standard Classification of Cultural and Ethnic Groups (ASCCEG).  This classification of cultural and ethnic groups is based on the geographic area in which a group originated or developed; and the similarity of cultural and ethnic groups in terms of social and cultural characteristics.  The classification is specific to Australian needs and was developed by the Australian Bureau of Statistics.  The classification is based on the self-perceived group identification approach, using a self assessed response to a direct question. This approach measures the extent to which individuals associate with particular cultural or ethnic groups.
Australia's first census was held in November 1828 in the colony of New South Wales.  Previous government statistical reports had been taken from "musters" where inhabitants were brought together for counting.  In 1828, the white population was 36,598 of whom 20,870 were free and 15,728 were convicts.  23.8% of the population were born in the colony.  24.5%  were women. There were 25,248 Protestants and 11,236 Catholics.  Indigenous Australians were not counted.
Of the 36,598, 638 were living in what is now Queensland.  There were also 18,128 people in Tasmania.
In the mid-19th century the colonial statisticians encouraged compatibility between the colonies in their respective censuses, and in 1881 a census was held simultaneously in each of the colonies.  This was part of a census of the British Empire.  The questions posed in the colonies were not uniform and Henry Heylyn Hayter, who conducted the Victorian census, found that this caused difficulties in dealing with Australia-wide data.
The population of Australia was 2,250,194.
Northern Territory was counted within South Australia (286,211) and was 3,451 plus 6,346 Aboriginals in settled districts.  The population of Western Australia did not include full-blood Aborigines.
The population of greater Melbourne was 282,947 and of Sydney was 224,939.
In 1901, there were 3,773,801 people (1,977,928 males and 1,795,873 females) counted in Australia.
Prior to Federation, each colony had been responsible for its own Census collection. The Census held during the first year of Federation, 1901, was again collected by each State separately.  When planning for the 1901 census it was clear that Federation was forthcoming, and a uniform census schedule was developed.
The first national census was developed by the Commonwealth Bureau of Census and Statistics.  The census occurred at midnight between 2 and 3 April 1911. Tabulation was carried out almost entirely by hand; over 4 million cards were sorted and physically counted for each tabulation. Results from the 1911 census took a long time to release with delays increased by World War I. The Australian population was counted as 4,455,005.
In the Census of 1911 many Collectors used horses. A drought in Western Australia meant that some Collectors were unable to find feed for their horses. Flooding and bogs stranded some Collectors in Queensland.

## Rubella research
In 1911 the Census asked about deaf-mutism. This question was also asked in the next two Censuses of 1921 and 1933.  Deaf-mutism was found to be very high among 10-14 year-olds, with the same pattern existing in the 1921 census among 20-24 year-olds.  The statisticians report on the 1921 cenus noted that it was "a reasonable assumption therefore that the abnormal number of deaf-mutes ... was the result of the extensive epidemic of infectious diseases which occurred soon after many in those age groups were born."  Rubella was not known to be a possible contributor.  During World War II, the ophthalmologist Norman McAllister Gregg began to investigate the connection between birth defects and the infection of mothers early in their pregnancy.  In 1951, prompted by Gregg's work, Australian statistician Oliver Lancaster examined the Census figures of 1911, 1921 and 1933.  He found a peak in the level of deaf-mutism in the age cohort born in 1898 and 1899 and that this matched with a known outbreak of rubella in those years.  "This was the first time in the world that the link between rubella and congenital problems with unborn children was firmly established." 
Australia's non-Abriginal population was counted in April 1921 as 5,435,700.  Indigenous Australians were listed separately.
One of the significant findings of the 1921 Census was the low rate of males to females in the 20-30 year age group, showing the impact of World War I on the population.
The 1921 census introduced automatic machine tabulation equipment, hired from England for the census.  Three punched cards were used to store individual, dwelling and family information. The cards were processed using an electric sorting machine prior to final totalling with an electric tabulator machine, devised by Herman Hollerith.
Following the 1967 referendum removing section 127 from the Constitution, the 'race' question was re-designed for the 1971 census and methods for remote area collection examined to improve identification of Indigenous origin.
There were 12,755,638 people counted.
The 1976 census was the largest undertaken, with 53 questions. Due to budgetary restraints, the Bureau was not able to complete normal processing of the data and a 50% sample was processed.
There were 13,548,450 people counted.
The census was held on Tuesday night of 6 August.  17,892,423 people were counted in Australia on Census Night.  Of these 342,864 people identified as Indigenous Australians.  There were 139,594 overseas visitors.
The census was held on Tuesday night of 7 August.  18,972,350 people were counted in Australia on Census Night.  Of these 410,003 people identified as Indigenous Australians.  There were 203,101 overseas visitors.
The most recent Australian census was conducted on Tuesday August 8, 2006.  19,855,288 people were counted in Australia on Census Night.  Of these 455,031 people identified as Indigenous Australians.  There were 206,358 overseas visitors.
The 2006 Census contained 60 questions, all of which were compulsory except those relating to religion and household census data retention.  The Census cost around AUD$300 million to conduct.  Question 60, relating to census data retention, asked: "Does each person in this household agree to his/her name and address and other information on this form being kept by the National Archives of Australia and then made publicly available after 99 years?"

## eCensus
For the first time in 2006, respondents were given the option of completing an online "eCensus" as opposed to the traditional paper based version.  By August 17, more than 720,000 households  had completed their census online.
Across Australia 8.4% of estimated dwellings lodged on line.  The highest percentage of internet lodgments was in the Australian Capital Territory with 14.8% of households using eCensus.  This was a markedly different proportion of households than elsewhere in Australia, with the other states and territory ranging from 5.9% take-up in the Northern Territory to 8.9% in Western Australia.
The peak lodgment was between 8pm and 9pm on Census night, when more than 72,000 online forms were received. During the 24-hour period of 8 August, eCensus delivered more than 12.5 million page views and at 8:47 pm  more than 55,000 households were logged on simultaneously.  However, availability of the product remained at 100% throughout the census period.  IBM assisted the Bureau of Statistics with this product.  Earlier in the year, IBM had provided similar infrastructure and technology for the Canadian census, in which over 2 million forms were completed using the Internet.