4. Census data collection

4.1 General

The data collection stage of the 2011 Census process ensured that each dwelling in Canada received a census questionnaire. The Census enumerated the entire population of Canada, which consists of Canadian citizens (by birth and by naturalization), landed immigrants and non-permanent residents, as well as family members living with them. Non-permanent residents are persons living in Canada on Census Day who have a work or study permit, or are claiming refugee status, as well as family members living with them here.

The census also counted Canadian citizens and landed immigrants who were temporarily outside the country on Census Day. This included federal and provincial/territorial government employees working outside Canada, Canadian embassy staff posted to other countries, members of the Canadian Forces stationed abroad and Canadians aboard merchant vessels.

In most urban areas, an Address Register is used to identify dwellings. This register is constructed before the census and covers about 80% of the dwellings included in the census. In the rest of the country, the list is prepared by interviewers using a Visitation Record in which they list private and collective dwellings, occupied or unoccupied, and agricultural operators and agricultural operations in their collection unit. These two registers serve as address listings for field operations and control purposes for data collection.

In the Census of Canada, various questionnaires are used to collect data, either online or in paper format:

• The 2A questionnaire is the basic questionnaire used to enumerate all private dwellings. Every household that receives a 2A census questionnaire is asked to list all household members who belong to the census population and answer questions for them.
• The 2C questionnaire is used to enumerate Canadians posted in other countries, including government employees (federal and provincial/territorial) and their families, and members of the Canadian Forces and their families.
• The 3A questionnaire is an individual census questionnaire used to enumerate persons in collective dwellings (each person in a collective dwelling must complete a separate questionnaire 3). It can also be used to enumerate usual residents in a private household who prefer to complete their own census questionnaire rather than be included in a 2A questionnaire with the other household members.

Wave methodology is an approach to data collection first used in the 2011 Census. Households are contacted at critical times to remind them to participate in the census and persuade them to complete the questionnaire. In each wave, households are provided with the information they need to respond. Based on the fact that every Canadian household is required by law to answer the census questions, the method is designed to encourage people to respond online, while mitigating the risk of a decline in overall response.

This new methodology varies with the collection method used to distribute the census materials in each region. These collection methods are described in the next section.

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4.2 Delivery methods and response modes

The three delivery methods used in the Canadian census are mail-out, list/leave and enumeration by interview. To make census collection as efficient as possible, Canada is divided into small geographic units known as collection units (CUs). In the 2011 Census, there were some 46,000 CUs in Canada.

Mail-out

For mail-out CUs, the postal system is used to deliver the census materials. This method requires an accurate address register and ensures effective, coordinated distribution, without the need to recruit and train a large contingent of enumerators. Mail-out CUs are typically in urban areas. While mail-out CUs now include about 80% of Canadian dwellings, they cover only a tiny fraction of the country's land area.

List/leave

List/leave CUs are typically in rural areas. In those areas, enumerators prepare a list of dwellings and deliver the census materials. About 18% of Canadian dwellings are in list/leave CUs, which cover a large portion of the country's land area.

Enumeration by interview

Enumeration by interview CUs are usually in remote or inaccessible places and in Aboriginal communities. To limit the number of trips that are often expensive and logistically complicated, that enumerators have to make to those places for follow-ups, they do more than prepare dwelling lists and deliver census materials, they also complete the questionnaires with the respondents on the spot. Interview CUs cover just over half of Canada’s land area, but only about 2% of its dwellings.

Response modes

The Internet response mode was introduced in the 2006 Census. In 2011, some 53.9% of Canadians used this method of responding, while 31.2% completed a paper questionnaire and mailed it back. In other words, 85.1% of respondents completed the questionnaire themselves. By comparison, in 2006, 17.8% of responses were submitted via the Internet and 60.6% by mail, for a total of 78.5% of questionnaires completed by respondents.

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4.3 Census wave methodology

Wave methodology was designed to encourage online response while offering an alternative for households that do not wish to complete their questionnaire online. This approach has many advantages for item response rates, questionnaire registration, question flow and data capture.

Wave methodology is applied differently in different CUs. Three main groups of CUs were defined, and a different wave methodology was developed for each one. Because of the nature of enumeration by interview CUs, however, no wave methodology was developed for them. The sections below and Figure 4.3.1 provide an overview of the wave methodology used in the 2011 Census.

Mail-out collection units – Wave 1 letter

First, a set of mail-out collection units was identified so that the households most likely to respond online could be targeted and those least likely to respond to the census, on the basis of results from the previous census, could be screened out. This set of CUs covers about 75% of the dwellings in mail-out areas. For this group of CUs, Wave 1 involved sending out a letter asking households to complete the questionnaire online using the secure access code (SAC) provided or call an automated system on a toll-free line to have a paper questionnaire mailed to them. The Wave 1 letters were delivered by the postal system one week before Census Day (i.e., on May 3, 2011).

Wave 2 was a reminder letter sent to all non-respondent households. The letter reminded the households that they were required by law to complete the census. Like the Wave 1 letter, it also provided the SAC and the toll-free telephone number. It was delivered to households between May 16 and 18, i.e., as early as six days after Census Day.

In Wave 3, a paper questionnaire was sent to non-respondent households. It was delivered to them between May 25 and May 31, i.e., as early as 15 days after Census Day. The households could still respond online using a SAC printed on the front cover of the questionnaire. The questionnaire was accompanied by a letter indicating that if the questionnaire was not completed by May 31, 2011, an enumerator would contact the household by telephone or in person to complete the questionnaire. It was also noted in the letter that if the household refused to answer the census questions, the case could be referred to the Public Prosecution Service of Canada, which would take appropriate action under the Statistics Act.

Wave 4, which began on June 1, 2011, consisted of field non-response follow-up (NRFU) and an automated reminder call. NRFU is described in Section 4.4 of this document.

Mail-out collection units – Wave 1 questionnaire

The second group of collection units on which a variant of wave methodology was used is the set of other mail-out CUs. This set of CUs covers about 25% of the dwellings in mail-out areas. Households in these CUs are considered, on the basis of 2006 Census data and administrative data, less likely to respond after receiving only a letter. Wave 1 for these CUs was the mailing of a paper questionnaire. The questionnaire provided an SAC, so that the household had the option of responding online. As in the case of the first group, Wave 1 took place one week before Census Day (May 3). Wave 2 for the second group was the same as for the first group. In Wave 3, the group's non-respondent households for which a telephone number was available in the census frame received an automated reminder call on May 24. Wave 4 for the second group was the same as for the first group.

List/leave collection units

The third group of collection units on which a variant of wave methodology was used is the set of all list/leave CUs. In Wave 1, enumerators delivered a paper questionnaire to all dwellings in those CUs on or about May 3. The questionnaire also provided an SAC, so that the household had the option of responding online. In Wave 2, all dwellings in these CUs received a thank-you/reminder card in the mail on May 10, whether they had responded or not, because it was generally impossible in these areas to send mail to specific addresses without the occupant's name. Wave 3, the last wave, involved going directly to field NRFU as of May 20.

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4.4 Verification of dwellings' occupancy status

Field operations were also carried out for the dwelling occupancy verification (DOV). The purpose of DOV, which began on May 13, 2011, was to identify a significant number of unoccupied or cancelled dwellings (addresses that are not private or collective dwellings) before NRFU started. Identifying such dwellings close to Census Day should make dwelling classification more accurate and perhaps easier to perform. DOV also reduces the NRFU workload, since any unoccupied or cancelled dwellings it identifies do not require follow-up.

Nevertheless, errors in classifying a dwelling as occupied or unoccupied do occur during collection. Some dwellings classified as unoccupied are in fact occupied, and some non-response dwellings are unoccupied. As a result, another operation, the Dwelling Classification Survey, is carried out after NRFU. It assesses and determines the occupancy status of dwellings for which no completed questionnaire has been received (unoccupied or cancelled dwellings and unresolved cases), for a sample of these dwellings. The survey's results are used to adjust the Census of Population counts during head office processing (see Section 5.7).

4.5 Non-response follow-up

As mentioned in Section 4.3 above, the final wave in the wave methodology is non-response follow-up (NRFU), which is carried out after dwelling occupancy verification. In that wave, enumerators telephone and visit households that have not responded. Each non-respondent household for which a telephone number was available receives an automated reminder call at the beginning of the NRFU period. The message reminded non-respondents of their legal obligation to respond to the census.

The enumerators had information from the Field Management System (FMS) to help them manage their work. A computerized system accessible over the Internet, the FMS was developed for the 2011 Census to facilitate the management of enumerators' work and the gathering of collection progress information.