Age, Sex at Birth and Gender Reference Guide, Census of Population, 2021

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Definitions and concepts

Age refers to the person’s age at last birthday before the reference date of May 11, 2021. Information on age is reported for the total population.^Note 1  The variable “age of person” is usually derived using the person's date of birth and the reference date. Age is expressed in single years ranging from 0 (less than one year) to the maximum number on the file.

Many age groups can be used, such as five-year age groups (e.g., 0 to 4, 5 to 9, 10 to 14, etc.), broad age groups (e.g., children aged 14 and under, 17 and under or 24 and under) and open age groups (e.g., 65 years and older, 85 years and older and 100 and older).

These are key age indicators:

• Population counts (in number) by age group.
  • Example: On May 11, 2021, the number of people aged 65 years and over had reached 7.0 million.

• Population change (in percentage) over the last five years by age group.
  • Example: Between 2016 and 2021, the number of seniors in the total population increased by 18.3%.

• Proportion, in percentage, of an age group.
  • Example: According to the 2021 Census, the population aged 0 to 14 represented 16.3% of the Canadian population.

• Mean age of a population, which is the average age of all its members.
  • Example: The mean age of the Canadian population in 2021 was 41.9 years.

• Median age of a population, where exactly one-half of the population is older and the other half is younger.
  • Example: The median age of the Canadian population in 2021 was 41.6 years.

The 2021 Census of Population introduces the concept of gender for the first time and makes the distinction between sex at birth and gender.

In the past, the census included the question “What is this person’s sex?” and the information pertaining to sex was collected according to two categories: male and female.

Beginning in 2021, sex at birth refers to sex assigned at birth, which is typically assigned based on a person's reproductive system and other physical characteristics. The census now asks “What was this person's sex at birth?” It also includes a note indicating that sex “refers to sex assigned at birth.” Information pertaining to sex at birth is collected on the census according to two categories: male and female. It is reported for the total population.

In addition to the question on sex at birth, the census now asks “What is this person's gender?” It also includes a note indicating that gender “refers to current gender, which may be different from sex assigned at birth and may be different from what is indicated on legal documents.” Information pertaining to gender is collected according to three options: male, female and a write-in option, “or please specify this person's gender.” It is collected for the total population, including for children aged 14 and younger.

Respondents answering for someone else living in their household (such as parents responding on behalf of their children) should answer, to the best of their knowledge, the gender they think the other household member would choose.

Gender refers to an individual’s personal and social identity as a man, woman or non-binary person (a person who is not exclusively a man or a woman).

Gender includes the following concepts:

• gender identity, which refers to the gender that a person feels internally and individually
• gender expression, which refers to the way a person presents their gender, regardless of their gender identity, through body language, aesthetic choices or accessories (e.g., clothes, hairstyle and makeup), which may have traditionally been associated with a specific gender.

A person’s gender may differ from their sex at birth, and from what is indicated on their current identification or legal documents such as their birth certificate, passport or driver’s license. A person’s gender may change over time.

Some people may not identify with a specific gender.

Sex at birth and gender refer to two different concepts but are interrelated. While sex at birth is primarily understood in terms of physical and biological features such as chromosomes, genitals and hormones, gender is a multidimensional concept that is influenced by several additional factors, including cultural and behavioural norms and self-identity.

Caution should be exercised when comparing counts for the sex at birth of person variable with counts for the gender of person variable. For most people, their sex at birth corresponds to their gender. However, some people’s gender may be different from their sex at birth. For example, in a given population, the group of persons of female sex does not necessarily correspond to the group of persons of female gender, although the two groups are generally very similar given the small size of the transgender and non-binary populations.

Beginning in 2021, the gender variable is expected to be used by default in most census standard data tables and analyses in accordance with the Treasury Board of Canada Secretariat’s Policy Direction to Modernize the Government of Canada’s Sex and Gender Information Practices (2018).

Information about sex at birth is needed to measure certain health and demographic indicators, such as life expectancy. The inclusion of questions on sex at birth and on gender allows all transgender and non-binary persons to report themselves fully in the census while facilitating historical comparability for demographic data.

Two variables on gender are produced: one is based on two categories and the other is based on three categories.

Depending on the data or the analytical product, the population may include children. In such instances, the terms “boy” and “girl” are preferred to “man” and “woman” when referring to children.

To maintain the balance between disseminating as much gender-based data as possible and preserving confidentiality, some information from the 2021 Census will be released at higher levels of geography using a three-category gender variable with the following categories:

• men (cisgender and transgender)
• women (cisgender and transgender)
• non-binary persons.

Given that the non-binary population is small, when necessary, a statistical method producing a two-category gender variable will be applied to prevent disclosure of identifiable data for lower levels of geography.

Consequently, in these cases, information will be aggregated and disseminated using the following categories:

• men+
• women+.

Individuals in the “non-binary persons” category are distributed in the other two gender categories and are denoted by the + symbol.

At higher levels of geography that allow for data disaggregation while maintaining confidentiality, certain information will be released using a five-category classification of cisgender, transgender and non-binary populations.

This is a derived variable that uses both three-category gender and sex at birth:

• cisgender men
• cisgender women
• transgender men
• transgender women
• non-binary persons.

The category “cisgender persons” refers to persons whose reported gender corresponds to their sex at birth. It includes cisgender (cis) men and women.

The category “transgender persons” refers to persons whose reported gender does not correspond to their sex at birth. It includes transgender (trans) men and women. Non-binary persons are excluded.

The category “non-binary persons” includes people whose reported gender on the census is not exclusively male or female. It includes persons whose reported gender is both male and female, neither male nor female, or either male or female in addition to another gender. It includes persons whose reported gender is, for example, agender, pangender, genderqueer, genderfluid, or gender-nonconforming. It also includes persons whose reported gender is Two-Spirit, a term specific to some Indigenous peoples of North America.

The classification of cisgender, transgender and non-binary supports the production and the publication of data on gender diversity, which includes transgender men and women, as well as non-binary persons.

For more information on these concepts, see the Dictionary, Census of Population, 2021, Statistics Canada Catalogue no. 98-301-X.

Note: Information on the historical comparability between the 2021 Census questions and those asked in earlier censuses is provided in the Concepts over time section of this document.

Questions

For the 2021 Census, the 2A short-form questionnaire was used to enumerate all usual residents of 75% of private dwellings. The 2A-L long-form questionnaire, which also includes the questions from the 2A short-form questionnaire, was used to enumerate a 25% sample of private households in Canada. For private households in First Nations communities, Métis settlements, Inuit regions and other remote areas, the 2A-R questionnaire was used to enumerate 100% of the population.

These questions appear in the 2021 Census: 2A questionnaire:

“Sex of person” is obtained from Question 2 (sex at birth):

2. What was this person's sex at birth?

Sex refers to sex assigned at birth.

• Male
• Female

“Gender of person” is obtained from Question 3 (gender):

3. What is this person's gender?

Refers to current gender, which may be different from sex assigned at birth and may be different from what is indicated on legal documents.

• Male
• Female
• Or please specify this person's gender:

“Age of person” is obtained from Question 4 (date of birth and age):

4. What are this person's date of birth and age?

If exact date of birth is not known, enter best estimate. For children less than 1 year old, enter 0 for age.

• Day
• Month
• Year
• Age

For more information on the reasons why the census questions are asked, please refer to the five fact sheets found on The road to the 2021 Census web page.

Classifications

The concepts and classifications pertaining to the age, sex at birth and gender variables conform to Statistics Canada’s standard definitions, which can be found here:

• age of person
• gender of person
• sex at birth of person.

Concepts over time

The introduction of the gender variable in the 2021 Census represents an addition to census content. In all censuses prior to the 2021 edition, individuals were only classified by sex (male or female) and not by gender. “Sex of person” was a commonly used cross-variable for nearly all other person-level census variables, essential to examining and understanding differences between men and women (or boys and girls) in the population.

Historical comparisons can be done using the “sex” variable prior to 2021 and that of “sex at birth” or the two-category gender variable in 2021, but the change in name, concept and definition must be clearly indicated.

It is anticipated that including sex (in census years prior to 2021) and the two-category gender variable (2021 Census) together in data tables and analyses related to any census topics will not result in a significant impact on historical trends, given the small size of the transgender and non-binary populations. According to the 2021 Census, 120,720 people in Canada were transgender or non-binary, over a total population of close to 37 million people.

Moreover, there is no way to know how transgender or non-binary respondents answered the question on sex (whether they answered male or female) in previous censuses. In some cases, it is possible that they provided the gender they most closely identify with, instead of their sex at birth.

For the 2016 Census, transgender, transsexual and intersex Canadians were informed that they could report the sex (male or female) with which they most closely associated themselves. Respondents who could not select one category when completing Question 2 on their census questionnaire had the option of leaving the question blank and indicating, in the “Comments section,” why this was the case.

The questions used in every census are based on extensive public consultations and testing. For the 2021 Census of Population Program, Statistics Canada consulted with the Canadian population on the content of the census questionnaire. This allowed Statistics Canada to gather information on data users and the uses of census data, and to evaluate if there were new ways to collect data from respondents who did not identify with the sex response categories.

The introduction of the concept of gender in the 2021 Census of Population, in addition to the updated concept of sex at birth, should help clarify the two concepts and improve data quality.

Prior to the 2021 Census, Statistics Canada conducted a census test in 2019 among nearly 135,000 households in Canada to determine whether new or revised questions under consideration could be easily understood and correctly answered. A technical report based on results from the 2019 Census Test was published along with the 2021 Census questionnaires.

As part of the 2021 Census releases, the two-category gender variable will be the standard in data tables and analyses except for the age release, where sex at birth will be used to produce the historical age pyramid. Any data tables or analyses released by gender with two categories should include a note mentioning:

Any data tables or analyses involving historical comparisons of the sex variable prior to 2021 and the two-category gender variable starting in 2021 should also include a note clearly indicating:

Any data tables or analyses involving historical comparisons of the sex variable prior to 2021 and the sex at birth variable starting in 2021 should also include a note clearly indicating:

For more information on comparability between the 2021 and 2016 censuses, please refer to the Guide to the Census of Population, 2021, Statistics Canada Catalogue no. 98-304-X.

Collection and processing methods

The COVID-19 pandemic emerged in Canada in early 2020 and affected all steps of the 2021 Census process, from data collection to dissemination. Please refer to the Guide to the Census of Population, 2021, Statistics Canada Catalogue no. 98-304-X, for more detailed information on this topic.

Information on gender on the census may be reported in terms of a person’s gender identity or expression, as well as how one is perceived by others, depending on whether information on gender is based on self-reported data or reported by proxy.

In the classification “gender of person,” the category “non-binary person” is derived from answers provided to the “or please specify [this person’s] gender” write-in option of the gender question. After data collection, write-in responses are recoded into either man, woman, non-binary person, or invalid categories, depending on the answers provided.

Only intentional (not a respondent error) and appropriate answers that clearly represent a different gender than either exclusively “male” or “female” are considered to produce “non-binary person” estimates.

For information on collection and processing methods, please refer to the Guide to the Census of Population, 2021, Statistics Canada Catalogue no. 98-304-X.

Data quality

The 2021 Census of Population underwent a thorough data quality assessment. The different certification activities conducted to evaluate the quality of the 2021 Census data are described in Chapter 9 of the Guide to the Census of Population, 2021, Statistics Canada Catalogue no. 98-304-X.

The data quality assessment was conducted in addition to the regular verifications and quality checks completed at key stages of the census. For example, throughout data collection and processing, the accuracy of specific steps such as data capture and coding was measured, the consistency of the responses provided was checked, and the non-response rates for each question were analyzed. As well, the quality of imputed responses was assessed during data editing and imputation.

During the data quality assessment, a number of data quality indicators were produced and used to evaluate the quality of the data. These indicators are briefly described below. Finally, resulting census counts were compared with other data sources and certified for final release.

The main highlights of this assessment of the data pertaining to age, sex at birth and gender are presented below.

Data quality indicators

A number of quality indicators were produced and analyzed during the 2021 Census of Population data quality assessment. Three indicators are available to data users for short-form content: the total non-response (TNR) rate, as well as the non-response rate and imputation rate per question.

The total non-response (TNR) rate is the primary quality indicator that accompanies each disseminated 2021 Census of Population product, and is calculated for each geographic area. It measures total non-response at the dwelling level. Non-response is said to be total when no questionnaire is returned from a dwelling or when a returned questionnaire does not meet the minimum content. More information on the TNR rate is available in Chapter 9 of the Guide to the Census of Population, 2021, Statistics Canada Catalogue no. 98-304-X.

Partial non-response is when answers to certain questions are not provided for a respondent household.

The non-response rate per question is a measure of missing information due to non-response to a question. For the short-form questionnaire, the non-response rate per question includes both TNR and partial non-response to the question.

It is defined as the total number of in-scope units for which no response was provided to the question, divided by the total number of in-scope units for the question. Here “units” refers to the statistical units for which data are collected or derived (e.g., persons or households, depending on whether the question is about a person-level characteristic or a household-level characteristic). A unit is considered to be in scope if it belongs to the census target population (i.e., private and collective dwellings occupied by usual residents) and if the question is applicable to that unit.

The imputation rate per question measures the extent to which responses to a given question were imputed. Imputation is used to replace missing data in the event of non-response or when a response is found to be invalid (e.g., multiple answers are provided when a single answer is expected). Imputation is conducted to eliminate data gaps and to reduce bias introduced by non-response. Imputation is generally done by identifying persons or households in the same geographical area with similar characteristics to the incomplete record and copying their values to fill in the missing or invalid responses.

The imputation rate per question is defined as the total number of in-scope units for which the response to that question was imputed, divided by the total number of in-scope units (see the definition of “units” provided in the above section on the non-response rate per question). For short-form content, imputation resolves both total and partial non-response (weighting is not done to adjust for total non-response, as it is for long-form content). Whole household imputation (WHI) is used to resolve total non-response. It first imputes the occupancy status of non-respondent dwellings and further imputes all the data for those dwellings resolved as occupied in the first step. WHI is included in the imputation rate per question, including the use of administrative data to impute non-responding households in areas with low response rates; see Appendix 1.7 of the Guide to the Census of Population, 2021, Statistics Canada Catalogue no. 98-304-X. As with the non-response rate, a unit is considered to be in scope if the question is applicable to that unit and the unit belongs to the census target population.

The non-response and imputation rates for a question are often similar, but some differences can be observed for a given question because of additional data processing steps that may have been required. These rates were regularly checked during data assessment, and a detailed analysis was done if there was a difference between the two rates for a question, to ensure the appropriateness of the processing steps taken and the quality of the data. A difference between the non-response rate and the imputation rate for a question can generally be explained by one of the following two factors:

• Some responses were considered invalid or inconsistent during the edit stage and imputation was needed, which is why the imputation rate is higher than the non-response rate for a question.
• Some non-responses were resolved in a straightforward manner early during data processing because a single resolution was possible based on the answers provided to other questions, making imputation unnecessary. This may explain why the non-response rate is higher than the imputation rate for a question.

Tables 2, 3 and 4 below present the non-response and imputation rates per question for Canada and for each province and territory.

The non-response and imputation rates per question at lower levels of geography are also available in 2021 Census data tables presenting data quality indicators. This information is scheduled for release on August 17, 2022 for short-form questions and on November 30, 2022 for long-form questions.

Certification of final counts

Once data editing and imputation were completed, the data were tabulated to represent the total Canadian population. Certification of the final counts was the last step in the validation process, which led to the recommendation to release the data for each level of geography and domain of interest. Based on the analysis of the data quality indicators and the comparison of the census counts with other data sources, the recommendation is for unconditional release, conditional release, or non-release (for quality reasons on rare occasions). For conditional release or non-release, appropriate notes and warnings are included in the products and provided to users. Moreover, other data sources were used to evaluate the census counts. However, since the risk of error often increases for lower levels of geography and for smaller populations, and the data sources used to evaluate these counts are less reliable or not available at these lower levels, it can be difficult to certify the counts at these levels.

Census counts are also subject to confidentiality rules that ensure non-disclosure of respondent identity and characteristics. For more information on privacy and confidentiality, please refer to Chapter 1 of the Guide to the Census of Population, 2021, Statistics Canada Catalogue no. 98-304-X. For information on how Statistics Canada balances the protection of confidentiality and the need for disaggregated census data, with specific attention to new 2021 Census content, please refer to Balancing the Protection of Confidentiality with the Needs for Disaggregated Census Data, Census of Population, 2021, Statistics Canada Catalogue no. 98-26-0005.

Data quality for age, sex at birth and gender

Age

In 2021, the non-response rate for age was 3.3% and the imputation rate was 3.7% (Table 2).

Two types of imputation are reflected in the imputation rate: total non-response (TNR) and question-level imputation as a result of non-response and invalid responses. At the national level, TNR accounted for 69.1% of all imputed records in 2021, and at the provincial and territorial level, it ranged from 61.7% for Prince Edward Island to 83.2% for Nunavut.

The 2021 imputation rate for age includes the use of administrative data to impute approximately 12,000 non-responding households in areas with low response rates (see Appendix 1.7 of the Guide to the Census of Population, 2021).

Sex at birth

The non-response rate for sex at birth in 2021 was 3.8% (Table 3). In 2021, 3.5% of the records for sex at birth at the national level were blank or invalid, and required imputation because they could not be resolved in a straightforward manner early in the data processing. The 2021 imputation rate for sex at birth includes the use of administrative data to impute approximately 12,000 non-responding households in areas with low response rates (see Appendix 1.7 of the Guide to the Census of Population, 2021).

At the provincial and territorial level, between 64.9% (Quebec) and 88.1% (Nunavut) of all imputed records for sex at birth were the result of TNR in 2021. At the national level, TNR accounted for 72.5% of all imputed records for sex at birth.

Gender

The non-response rate for gender in 2021 was 4.0% at the national level, and the imputation rate was similar at 3.9% (Table 4).

Of the imputed records for gender, approximately 65% were the result of TNR at the national level. At the provincial and territorial level, between 56% and 85% of all imputed records were the result of TNR.

Comparability of concepts over time

Consistent with trends across many census cycles, the census data reflect a gradual aging of the population as the large baby boom cohort born between 1946 and 1965 moves through the age structure. By 2021, this cohort was aged 56 to 75.

There is generally a slightly larger share of females than males across census years although this gap has been converging over time (Table 6). In 2021, based on sex at birth, females composed 50.7% of the population while males composed 49.3%.

Given that the gender question was added in the 2021 Census, there are no comparable previous census data. In 2021, there were 46,725 non-binary persons, representing 0.13% of the total population.

Comparability with other data sources

Age and sex at birth

As a standard practice, the quality of the 2021 Census age and sex at birth information was evaluated internally prior to publication. The data were compared, to the extent possible, with alternative data sources.

Census age and sex at birth data for 2021 were compared with results from previous census cycles, as well as Statistics Canada’s program data from the Annual Demographic Estimates: Canada, Provinces and Territories; the Annual Demographic Estimates: Subprovincial Areas; and the Annual Income Estimates for Census Families and Individuals (T1 Family File). The Demographic Estimates Program bases its postcensal estimates of population by age and sex at birth using the cohort component approach and several administrative sources of information such as the Vital Statistics Program; immigration files from Immigration, Refugees and Citizenship Canada; and fiscal data from the Canada Revenue Agency.

For specific age groups and their sex at birth, the following alternative data sources were used:

• Births from the Vital Statistics Program were used to compare with the 2021 Census for age 0.
• Old Age Security Program information prepared by the Office of the Chief Actuary was used to compare with the 2021 Census for ages 70 and older.

Overall, 2021 Census age and sex at birth data compared well with other data sources.

Gender

The data were compared with other available sources and there was an overall coherence^Note 2 although unweighted counts from survey data are generally low. The census is the best source of data for small populations.