2011 Census processing
During the first two weeks of May 2011, 80% of Canadian households received letters or census questionnaires through the mail, while the remaining 20% had their questionnaires delivered by an interviewer. Respondents were asked to answer the census questions online or to mail back a completed paper questionnaire.
The next phase in the census process began as early as May 3, since households could choose to complete their forms online as soon as they received their paper questionnaire. This phase began with the process of translating responses from approximately 13.5 million households into meaningful data. This part of the census cycle is known as the processing phase and is divided into the following main activities:
Table of contents
Data processing staff in Gatineau, Quebec are responsible for the registration of completed census questionnaires. Initial registration, via the reading of barcodes through the see-through portion of the return envelope, is conducted by Canada Post.
For the 2011 Census, Canada Post delivered the mailed-back paper questionnaires to the Data Operations Centre, while electronic questionnaires were transmitted directly to Statistics Canada in Ottawa. Electronic questionnaires were registered automatically and paper questionnaires were checked in by scanning the barcode on the front of the questionnaire.
As the collection activities wind down, the registered paper questionnaires are moved to the next step in processing activities.
The 2011 Census captured data automatically using automated capture technologies rather than manual keying.
Steps in imaging
Document preparation - mailed-back questionnaires are removed from envelopes, and foreign objects such as paper clips and staples are removed in preparation for scanning. Forms that are in the booklet format are separated into single sheets.
Scanning - using high-speed scanners, paper questionnaires are converted to digital images (pictures).
Automated data capture - optimal mark recognition and intelligent character recognition technologies are used to extract respondents’ data. Where the systems cannot recognize the handwriting, data repair will be done by an operator.
Check-out - as soon as the questionnaires have been processed through all of the above steps, the paper questionnaires are checked out of the system. Check-out is a quality assurance process that ensures the images and captured data are of high enough quality so that the paper questionnaires are no longer required.
Some automated completion-editing, simulating edits an interviewer would have done in previous censuses, are performed at this stage to check for completeness, consistency and coverage. Multiple responses for one household may be received and flagged for subsequent interactive verification if an error is identified.
When a missing or invalid response is uncovered, interactive verification may be used to resolve failures by manually examining the captured data and scanned images (where available) to help determine the appropriate response. When necessary, failed household questionnaire data are transmitted to a collection support office for follow-up. The data is transmitted back to the Data Operations Centre and reintegrated into the system for subsequent processing.
The census questionnaire contains questions where answers can be checked off against a list, as well as questions where the respondent must write in answers in the boxes provided. These written responses must be converted to numerical codes before they can be tabulated for release purposes. For the 2011 Census, all written responses on the questionnaires undergo automated and computer-assisted coding to assign each one a numerical code using Statistics Canada reference files, code sets and standard classifications. Reference files have been built using actual responses from past censuses for the automated match process. Specially trained coders and experts resolve cases that cannot be assigned automatically.
The variables for which coding will apply are:
- Relationship to Person 1
- Home language
- Mother tongue
In 2011, it is expected that over 13 million write-ins will be coded, of which an average of about 85% will be coded automatically.
The data collected in any survey or census contains omissions or inconsistencies. These errors can be the result of respondents missing a question, or they can be due to errors generated during processing. For example, a respondent may forget to answer a question. Census staff may code responses incorrectly or may make other mistakes during processing.
After the capture, initial editing, and coding operations are complete, the data are processed through the final edit and imputation activity. The final editing process detects errors and the imputation process corrects them. The edit and imputation phase is important because:
- Consistent estimates are essential to users, particularly those counts that are used as official estimates for legislative and administrative purposes.
- If invalid or missing responses are not adjusted, data users would have to tabulate incomplete data or develop their own estimates, which would not be consistent with other results.
- Many data users do not wish to adjust or tabulate incomplete data.
- Correct data are necessary for processing purposes. For example, family patterns are constructed based on information provided by respondents on age, sex, marital status, relationship to Person 1, etc. If these data are missing or inconsistent, family characteristics cannot be compiled.
Glossary of terms
census - a statistical portrait of Canada. The census collects demographic, social and economic information about people, housing units and agricultural operations in Canada.
collection unit (CU) - the small geographic area used to outline manageable areas for census data collection. In remote areas it is the unit for which an interviewer is responsible. There were 47,000 collection units for the 2011 Census.
list/leave - refers to the delivery (as opposed to mail-out) of questionnaires to 20% of dwellings in Canada by a census interviewer.
visitation record (VR) - is a document used by interviewers in list/leave areas to record summary information about each dwelling. There is one VR for each collection unit.
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