Census of Population - Dwelling Classification Survey (DCS)

Detailed information for 2021




Every 5 years

Record number:


The Dwelling Classification Survey produces estimates of under-coverage arising from non-response and occupied dwellings misclassified as unoccupied during the Census of Population.

Data release - These data are not released to the public.


This survey is used to correct census counts, for dwellings wrongly classified as unoccupied and dwellings identified as occupied for which the census was unable to find a contact, by collecting information on the characteristics of the occupants of those dwellings (also referred to as non-response dwellings).

In June and July 2021, Statistics Canada is conducting the Dwelling Classification Survey (DCS), which is part of the Census Program. Employees visit a sample of dwellings to determine whether the dwelling was occupied on Census Day (May 11, 2021) to evaluate the quality of data collected during the Census of Population.

Collection period: June through July, every (5) five years


  • Population and demography

Data sources and methodology

Target population

The DCS target population consists of all dwellings classified as either unoccupied or non-response dwellings, excluding dwellings in collective collection units (CU), canvasser CUs and Indian reserves CUs. These areas are excluded because of cost and operational considerations.

Instrument design

The questionnaire was tested in the field in June 2019. It was last revised for the 2021 DCS and questionnaire design specialists were consulted.


This is a sample survey with a cross-sectional design.

The sampling frame consists of all self-enumeration CUs. Since Nunavut has no in-scope CUs, the DCS is not conducted in Nunavut. The sample design is as follows. First, all in-scope CUs in the Yukon and in the Northwest Territories form one stratum. All of these CUs are selected for the DCS sample with certainty. All of the CUs in Prince Edward Island form a second stratum from which a simple random sample is selected.

The remaining CUs are grouped into urban and rural strata. A CU is considered urban if it is initially part of a census metropolitan area (CMA) or a census agglomeration (CA) that has 40,000 or more occupied dwellings. Further, all of the CUs within a crew leader district (CLD) are considered urban if more than 50% of the CUs in the CLD are urban. All of the remaining CUs form the rural strata. Urban CUs are stratified by CMA and CA. A simple random sample of at least five CUs is selected within each stratum. From past census data, it was determined that five CUs was an appropriate workload for an interviewer. In order to control field costs, the rural sample is chosen to be geographically close. This is done via a two-stage stratified random sampling design. In the first stage, CLDs are selected within each province. In the second stage, five CUs are selected from each of the selected CLDs.

Sub-sampling of dwellings within a sampled CU is invoked when the number of unoccupied and non-response dwellings exceeds a maximum dwelling parameter. Otherwise, all unoccupied dwellings and non-response dwellings in the sampled CUs form the DCS sample of dwellings. The DCS sample size is usually around 1,700 CUs and 55,000 dwellings.

Data sources

Data collection for this reference period: 2021-06-14 to 2021-08-13

Responding to this survey is mandatory.

Data are collected directly from survey respondents.

The 2021 Census reference date is May 11, 2021

Respondents are required, under the authority of the Statistics Act, to answer all the survey.

Sampled dwellings in the sampled CUs that are classified as unoccupied on Census Day or classified as occupied but for which no census form has been returned, are to be checked again to determine the true occupancy status of the dwellings on Census Day. A DCS questionnaire is used for this purpose.

In order to determine occupancy status and collect other information, enumerators are instructed to contact current occupants, neighbors, landlords, or any other person with some knowledge about the dwelling. Up to three contact attempts are made for each dwelling. If the dwelling is found to be occupied on Census Day, the number of occupants on Census Day and their age and sex are also obtained.

View the Questionnaire(s) and reporting guide(s) .

Disclosure control

Statistics Canada is prohibited by law from releasing any information it collects that could identify any person, business, or organization, unless consent has been given by the respondent or as permitted by the Statistics Act. Various confidentiality rules are applied to all data that are released or published to prevent the publication or disclosure of any information deemed confidential. If necessary, data are suppressed to prevent direct or residual disclosure of identifiable data.

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