As the graph shows, since the 1967 referendum, there have been large increases from one census to the next in the number of people who indicated that they were of Aboriginal or Torres Strait Islander origin. Although one might expect a big jump in 1971 (the first Census after the 1967 referendum) followed by a leveling off, the increase has instead been gradual and sustained, and the increases from one census to the next are larger than can be explained by demographic factors (births, deaths and migration). For example, only about half of the increase between 1991 and 1996 can be explained by demographic factors. The rest of the increase is most likely explained by an increased willingness of people to indicate their Indigenous origin on a government form. (Improved enumeration of Indigenous people by the Australian Bureau of Statistics may also have contributed.). As has been the case in many developed countries, it has often been in the interests of Indigenous people to avoid being identified as such by the government. (For example, see background information on the The National Inquiry into the Separation of Aboriginal and Torres Strait Islander Children from Their Families, available at the Human Rights and Equal Opportunities Commission website on http://www.hreoc.gov.au/social_justice/
stolen_children/index.html.)

Australian census forms are destroyed immediately after they are processed, and it is not possible to link people’s records over time to identify those people who changed the way they answered the question, so it is difficult to characterize them.

For more information about these issues, see Ross K., 1999. Occasional Paper: Population Issues, Indigenous Australians, 1996. ABS cat. no. 4708.0, Australian Bureau of Statistics, Canberra. (Available on-line at http://www.abs.gov.au/Ausstats/
ABS%40.nsf/525a1b940214123
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OpenDocument.)