@Northern Light https://www.statcan.gc.ca/en/hp/estima
Hat tip to the questioner and the response from Statcan here:
Very good catch, let me bring forward some of what Stats Can says on their page:
First this:
"The 2021 Census counted 36,991,981 people in Canada during the national enumeration with reference date May 11, 2021. This count is lower than the preliminary postcensal population estimate of 38,201,103 people calculated for the same reference date.
The difference between the two figures is not unexpected and is similar to that which was experienced for previous censuses. This note outlines why there are differences between census counts and population estimates."
Bolding is my emphasis.
My comment: It should be unexpected; if you believe you consistently produce an incorrect number; and it is consistently an undercount, and you later apply some formula to up that number retroactively, you're doing something wrong!
Some margin of error is to be expected; but if it consistently varies in the same direction, it is indicative of a consistent mistake; one that can and should be corrected.
Commentary:
If the undercount is consistent across multiple census' Then you don't need to undertake a detailed study, you apply the corrective formula from last time; and the time before, and since it should be embedded in your system already, it should be available simultaneously to the original census data.
Further, how in the hell did it take 8 months to release the top-level data of a census that was completed electronically?
And how it could possibly take another 19 months to issue corrected data?