Detailed explanation: Differences between Statistics Canada's census counts and population estimates

The 2011 Census counted 33,476,688 people in Canada during the national enumeration with reference day May 10, 2011. This count is lower than the published July 1, 2011 population estimate of 34,482,779 people. The difference between the two figures is not unexpected and is similar to that which was experienced in the 2006 Census. This note outlines why there are differences between census counts and population estimates.

The objective of a census is to provide detailed information on the population at a single point in time. In this respect, one of its goals is to enumerate the entire population. Inevitably, however, some people are not counted, either because their household did not receive a census questionnaire (for example, if a structurally separate dwelling is not easily identifiable) or because they were not included in the questionnaire completed for the household (for example, the omission of a boarder or a lodger). Some people may also be missed because they have no usual residence and did not spend census night in any dwelling. In contrast, a small number of people may also be counted more than once (for example, students living away from home may have been enumerated by their parents and by themselves at their student address).

To determine how many individuals were missed or counted more than once, Statistics Canada conducts postcensal coverage studies of a representative sample of individuals. Results of these studies in combination with the census counts are used to produce current population estimates which take into account net undercoverage.

Postcensal coverage study results are usually available two years after enumeration date. For the 2006 Census, preliminary postcensal study results were released in March 2008. Final estimates of coverage error were subsequently released in September 2008.

For the 2011 Census, preliminary coverage study will be released in March 2013 and the results of the final study will be released in September 2013. These will in turn be used to revise and update the population estimates based on the 2011 Census results. Consequently, a series of revised population estimates for the period 2006 to 2013 will be disseminated in September 2013.

One of the advantages of the census is to provide counts for small regions (below the census division level) for which demographic estimates are not available or are less precise. On the other hand, population estimates provide a more accurate measure of population counts. In addition, estimates are utilized to measure the evolution of the population between censuses and provide explanations behind the population growth. They are available on a quarterly and annual basis at the national, provincial and territorial levels and are also available at the subprovincial level on an annual basis.

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