Coverage Technical Report, Census of Population, 2016
1. Estimates of population coverage errors

1.1 Introduction

The census defines the population to be counted and the rules by which the population is to be counted (see Section 3). Coverage errors occur when errors are made relative to these definitions and rules. The main sources of coverage errors include the failure to include a dwelling (and, in turn, failing to include its residents), and respondent error by not including all persons who should be included or by including persons who should not be included. This section presents estimates of 2016 Census population net undercoverage, undercoverage and overcoverage. Undercoverage and overcoverage may lead to bias in official counts and estimates because the characteristics of the persons not included may differ from those of persons who are included, and the characteristics of those counted more than once (duplicates) may differ from those of persons who were counted only once. Net undercoverage indicates the extent to which the number of enumerations included in census data is higher or lower than complete enumeration.

1.2 Net undercoverage

The 2016 Census population net undercoverage rate was estimated at 2.36%.^{Note 1} In other words, the difference between the number of persons who were not included in the census but were members of the census target population and the number of duplicates was estimated to be 2.36% of the census target population. The population undercoverage rate is estimated at 4.32% (1,557,061 persons), while the population overcoverage rate is estimated at 1.96% (707,335 persons). An undercoverage rate of 4.32% indicates that persons who were not included but who were part of the target population represent 4.32% of the census target population. An overcoverage rate of 1.96% indicates that duplicate enumerations represent 1.96% of the census target population.

The estimated undercoverage and overcoverage rates have both increased compared with the 2011 Census. The net undercoverage rate, which is the difference between undercoverage and overcoverage, increased slightly.

Since the primary goal of census coverage studies is always to produce the best coverage estimates possible for the most recent census, their methodology for the 2016 Census, as described in sections 7 and 8, has been improved. However, these improvements limit the comparability of these estimates with the 2011 net undercoverage estimates and partly explain the difference observed. In addition, since the net undercoverage estimates are measured from samples, the margin of error associated with the 2011 and 2016 estimates may also partly explain the difference.

This section presents estimates of net undercoverage based on the following geographic and demographic variables:

• province or territory of current residence at the time of the census
• age and sex
• marital status and sex
• mother tongue
• census metropolitan area (CMA) of the usual place of residence on Census Day.

Table 1.2b provides an estimate of net undercoverage, standard errors related to the estimate, and the corresponding estimated net undercoverage rate and standard error for various characteristics. Negative net undercoverage estimates indicate that the overcoverage rate was higher than the undercoverage rate. For an explanation of how this can occur, see Section 9.

The standard error provides an indication of the accuracy of sampling-based estimates. An interval covering two standard errors on both sides of the estimate includes the correct value 19 times out of 20. In other words, there are approximately 19 chances out of 20 (95%) that the actual population net undercoverage rate for the 2016 Census was between 2.12% and 2.60% (i.e., 2.36% ± two standard errors), or about 2 chances out of 3 (68%) that the actual rate was between 2.24% and 2.48% (i.e., 2.36% ± one standard error).

Since net undercoverage reflects both undercoverage and overcoverage, the reader should also consult the undercoverage and overcoverage estimates in Table 1.3. A low net undercoverage rate, for example, may reflect a low undercoverage rate, or a high undercoverage rate combined with a high overcoverage rate.

The highest population net undercoverage rates in the country were observed in two of the three territories: the Northwest Territories, which had the highest rate (6.57%), followed by Yukon (6.20%). Among the provinces, British Columbia had the highest net undercoverage rate, 4.07%, followed by Saskatchewan (3.07%), Alberta (2.77%) and Ontario (2.76%). Quebec had the lowest population net undercoverage rate, at 0.43%, followed by Newfoundland and Labrador (1.85%) and Nova Scotia (1.89%). In 2011, the highest rates were observed in the three territories, while New Brunswick had the lowest rate. As previously mentioned, improvements made to the methodology of the 2016 Census coverage studies limit the comparability of estimates with those of 2011 net undercoverage.

Population net undercoverage was generally higher for males, and highest for young adults. The net undercoverage rate for males was more than twice the rate for females, 3.32% compared with 1.41%. In the general population, net undercoverage was highest in the 20 to 34 age group for both men and women. It stood at 6.13% among persons aged 20 to 24, and 6.41% among those aged 25 to 34. For men, the highest net undercoverage rate was 8.19% among men aged 20 to 24, and 8.15% among men aged 25 to 34. For women, this rate reached 4.64% among those aged 25 to 34. Contrary to what was observed among men, the net undercoverage rate of women aged 20 to 24 was quite similar to the rate noted for women aged 18 to 19 (3.89%, compared with 4.04%). For women aged 55 and older and men aged 65 and older, the net undercoverage rate was negative, which indicates more excess enumerations than persons who were not enumerated.

The net undercoverage rate of the population aged 15 and older was higher for separated persons (11.61%), especially for males (17.65%). It was also high for single persons (6.31%), i.e., persons who had never legally married and who were not in a common-law union.

The net undercoverage rate for those whose mother tongue is English was higher than for those whose mother tongue is French (1.79%, compared with 0.04%). The net undercoverage rate for allophones, persons whose mother tongue is neither English nor French, was higher (5.88%).

Net population undercoverage was slightly more frequent in CMAs than outside them. Nationally, net undercoverage was 2.45% for those who should have been enumerated in CMAs. This was slightly higher than the net undercoverage rate for those not living in a CMA (2.15%). Only Manitoba and Alberta had a higher rate outside CMAs than within them.

1.3 Undercoverage

Undercoverage generally referred to persons who were not included as usual residents in the questionnaire that was completed for their usual residence, or persons for whom no questionnaire was completed for their usual residence. For example, persons who regarded their residence as temporary may not have been included as usual residents elsewhere. Persons without a usual place of residence (e.g., the homeless) were also much more subject to undercoverage.

This section presents undercoverage estimates based on the following geographic and demographic variables:

• province or territory of current residence at the time of the census
• age and sex
• marital status and sex
• mother tongue
• census metropolitan area (CMA) of the usual place of residence on Census Day.

Table 1.3 provides the estimated undercoverage regarding the number of persons not included, the standard error of the estimate, the corresponding estimated undercoverage rate, and its standard error. In some instances, undercoverage estimates are negative (e.g., ‑1,269 persons in the Peterborough CMA). For an explanation of how this can occur, see Section 9.

There were some demographic trends in undercoverage. The rate of undercoverage for males was more than one-and-a-half times the rate for females, or 5.27% compared with 3.39%. The undercoverage rate was highest for young adults aged 18 to 34 (men and women). Among young men, undercoverage was 11.46% for those aged 20 to 24 and 10.44% for those aged 25 to 34.

In terms of marital status, undercoverage was highest among those aged 15 or older who were separated and not in a common-law union, at 13.03%. It was also high for single persons not in a common-law union, at 8.93%. In both cases, these rates were higher for men than for women.

Table 1.3 shows that the persons most likely to have been missed in the 2016 Census were men aged 18 to 34 who were single (who were never married and not in a common-law union), and separated persons. Mother tongue was also significant for undercoverage rates because undercoverage rates were lower among those whose first language was French (2.29%), followed by those whose first language was English (3.71%). For persons whose mother tongue was neither English nor French, the rate was even higher, at 7.69%.

1.4 Overcoverage

Population overcoverage is the number of excess enumerations in the census counts for persons enumerated more than once (usually twice). This error produces bias because these persons should have been enumerated only once. Examples of overcoverage include children whose parents live separately who were included on each parent’s census questionnaire, persons who do not live with their family for work reasons who are listed on their family’s form and also on the form for the dwelling they live in while working, and students away at school who are listed both by their roommates and by their parents.

This section presents estimates of overcoverage based on the following geographic and demographic variables:

• province or territory of current residence at the time of the census
• age and sex
• marital status and sex
• mother tongue
• census metropolitan area (CMA) of the usual place of residence on Census Day.

Table 1.3 also contains estimates of the number of excess enumerations and the associated standard error.

The standard errors for overcoverage estimates found in Table 1.3 were lower than those for undercoverage. As indicated below, certain demographic trends emerged from overcoverage estimates.

Across the provinces and territories, the estimated overcoverage rate varied less than the estimated undercoverage rate. In fact, the gap between the lowest rate and the highest rate among all provinces and territories was 0.99 percentage points for overcoverage (with the rate varying between 1.25% and 2.24%), whereas this gap was 5.85 percentage points for undercoverage (with the rate varying between 2.57% and 8.42%). Males and females had similar overcoverage rates, at 1.95% compared with 1.98%. Overcoverage was higher for children and young adults aged 5 to 24. As mentioned, these high rates were largely attributable to multiple enumerations of children in shared custody and students.

For marital status, the overcoverage rate was higher for persons who had never been married and who were not in a common-law union (2.45%). This phenomenon was observed equally among women and men, and was consistent with the results by age.

In summary, Table 1.3 presents the profile of persons most likely to be counted more than once; they were equally likely to be male or female, and more likely to be a child or a young adult. For persons aged 15 and older, single persons were more likely to be counted more than once.

Notes

• Previous
• Next