Why does Census population differ from estimates in Census years?
In Canada, a Census of the population is undertaken every five years. While the objective of this exercise is to count everybody in the country, in reality some people are inevitably missed and in some cases, people get counted more than once. Statistics Canada conducts a number of post-censal surveys to develop an estimate of the net difference between those who were missed and those who were counted more than once and this net undercount (typically more people are missed than over counted) is then applied to the Census population to develop an estimate of the overall population. The estimate is also adjusted for the timing difference between the population on Census day (mid-May) and the estimates reference date of July 1.
