The projections consider the population who, in the 2001 Census, declared that they had an Aboriginal identity and/or were Registered or Treaty Indians (as defined by the Indian Act of Canada) and/or were members of an Indian Band. There were 952,900 people with at least one Aboriginal identity, most of them identifying with only one Aboriginal group (946,200). A small number of people, less than 6,700, indicated belonging to more than one Aboriginal group. In addition, 23,400 people just reported their status as a Registered or Treaty Indian or a member of an Indian Band. Together, this gave a base population of 976,300 people. Before using this population as the base for projections, two modifications to the 2001 Census counts were made.

First, it was necessary to assure that those persons who indicated that they belonged to more than one Aboriginal group were considered only once in the model, and that 23,400 people who didn't identify Aboriginal were also included. This modification did not change the overall size of the Census Aboriginal population (976,300), but introduced small changes to the size of the North American Indian population as 635,700 (instead of 608,800), the Métis population as 295,100 (instead of 292,300) and the Inuit population as 45,500 (instead of 45,100).

Second, the census data was corrected for situations when the census didn't count all those who should have been counted. The population living on-reserve was adjusted to take into account incompletely enumerated reserves. In each census, on some Indian reserves and settlements, enumeration is not permitted or is interrupted before it is completed. Estimates of the number of people not counted were made and added to the census number of persons living on reserves. Also, during each census enumeration, there are people who cannot be counted for various reasons (their dwelling was missed, they were not included on the census questionnaire, etc.) or who are counted more than once. Adjustment for these situations was made for the Aboriginal populations living on enumerated reserves and outside the reserves. These adjustments increased the size of the total Aboriginal population and that of specific groups.