Sampling and Weighting Technical Report, Census of Population, 2021
Introduction
The 2021 Census Program enumerates Canadian households using two main types of questionnaires: the short-form questionnaire and the long-form questionnaire. In 2021, a sample of 25% of Canadian households received a long-form questionnaire, which included the questions from the short-form questionnaire. The other households received the short-form questionnaire.
In addition to the short-form questions, the long-form questionnaire includes a series of questions to paint a full portrait of the Canadian population and households, according to their demographic, social and economic characteristics.
The estimates produced from responses to the questions on both questionnaires are obtained from the entire population via a census. All households that respond to both types of questionnaires contribute to a specific number, such as the population figure for a specific age group.
The estimates produced from responses to at least one question found only on the long-form questionnaire are obtained from the sample. In those cases, only respondent households in the long-form sample contribute to the estimate. The highest level of educational attainment is an example of this type of estimate.
The long-form sample is evenly distributed geographically to ensure a high degree of reliability of the estimates for all areas of the country and to grant the same degree of importance to all geographic units of a given size.
This technical report presents the methodology used to produce the estimates based on the 2021 Census of Population long‑form sample. Chapter 1 details the collection methods used for the census and for the long‑form sample. Chapter 2 describes how the sampling was applied for the long-form questionnaire. Chapter 3 explains the data processing procedures. Chapter 4 gives an overview of the procedures used to assign weights to the respondent units in the long-form sample to obtain estimates for the population. Chapter 5 covers different evaluations of the weighting procedures, while Chapter 6 provides an overview of the variance estimation methodology used for the 2021 Census long-form sample. Chapter 7 introduces statistical inference using confidence intervals. A conclusion follows.
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