Frames and coverage
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- 1. Overcoverage in the 2011 Canadian Census ArchivedSurveys and statistical programs – Documentation: 11-522-X201300014269Description:
The Census Overcoverage Study (COS) is a critical post-census coverage measurement study. Its main objective is to produce estimates of the number of people erroneously enumerated, by province and territory, study the characteristics of individuals counted multiple times and identify possible reasons for the errors. The COS is based on the sampling and clerical review of groups of connected records that are built by linking the census response database to an administrative frame, and to itself. In this paper we describe the new 2011 COS methodology. This methodology has incorporated numerous improvements including a greater use of probabilistic record-linkage, the estimation of linking parameters with an Expectation-Maximization (E-M) algorithm, and the efficient use of household information to detect more overcoverage cases.
Release date: 2014-10-31 - Articles and reports: 12-001-X20060029551Description:
To select a survey sample, it happens that one does not have a frame containing the desired collection units, but rather another frame of units linked in a certain way to the list of collection units. It can then be considered to select a sample from the available frame in order to produce an estimate for the desired target population by using the links existing between the two. This can be designated by Indirect Sampling.
Estimation for the target population surveyed by Indirect Sampling can constitute a big challenge, in particular if the links between the units of the two are not one-to-one. The problem comes especially from the difficulty to associate a selection probability, or an estimation weight, to the surveyed units of the target population. In order to solve this type of estimation problem, the Generalized Weight Share Method (GWSM) has been developed by Lavallée (1995) and Lavallée (2002). The GWSM provides an estimation weight for every surveyed unit of the target population.
This paper first describes Indirect Sampling, which constitutes the foundations of the GWSM. Second, an overview of the GWSM is given where we formulate the GWSM in a theoretical framework using matrix notation. Third, we present some properties of the GWSM such as unbiasedness and transitivity. Fourth, we consider the special case where the links between the two populations are expressed by indicator variables. Fifth, some special typical linkages are studied to assess their impact on the GWSM. Finally, we consider the problem of optimality. We obtain optimal weights in a weak sense (for specific values of the variable of interest), and conditions for which these weights are also optimal in a strong sense and independent of the variable of interest.
Release date: 2006-12-21 - 3. A synthetic, robust and efficient method of making small area population estimates in France ArchivedArticles and reports: 12-001-X19970023620Description:
Since France has no population registers, population censuses are the basis for its socio-demographic information system. However, between two censuses, some data must be updated, in particular at a high level of geographic detail, especially since censuses are tending, for various reasons, to be less frequent. In 1993, the Institut National de la Statistique et des Études Économiques (INSEE) set up a team whose objective was to propose a system to substantially improve the existing mechanism for making small area population estimates. Its task was twofold: to prepare an efficient and robust synthesis of the information available from different administrative sources, and to assemble a sufficient number of "good" sources. The "multi-source" system that it designed, which is reported on here, is flexible and reliable, without being overly complex.
Release date: 1998-03-12 - Articles and reports: 12-001-X199500114411Description:
In 1991, Statistics Canada for the first time adjusted the Population Estimates Program for undercoverage in the 1991 Census. The Census coverage studies provided reliable estimates of undercoverage at the provincial level and for national estimates of large age - sex domains. However, the population series required estimates of undercoverage for age - sex domains within each province and territory. Since the direct survey estimates for some of these small domains had large standard errors due to the small sample size in the domain, small area modelling techniques were needed. In order to incorporate the varying degrees of reliability of the direct survey estimates, a regression model utilizing an Empirical Bayes methodology was used to estimate the undercoverage in small domains. A raking ratio procedure was then applied to the undercoverage estimates to preserve consistency with the marginal direct survey estimates. The results of this modelling process are shown along with the estimated reduction in standard errors.
Release date: 1995-06-15 - Articles and reports: 12-001-X199400214422Description:
Dual system estimation (DSE) has been used since 1950 by the U.S. Bureau of Census for coverage evaluation of the decennial census. In the DSE approach, data from a sample is combined with data from the census to estimate census undercount and overcount. DSE relies upon the assumption that individuals in both the census and the sample can be matched perfectly. The unavoidable mismatches and erroneous nonmatches reduce the accuracy of the DSE. This paper reconsiders the DSE approach by relaxing the perfect matching assumption and proposes models to describe two types of matching errors, false matches of nonmatching cases and false nonmatches of matching cases. Methods for estimating population total and census undercount are presented and illustrated using data from 1986 Los Angeles test census and 1990 Decennial Census.
Release date: 1994-12-15 - Articles and reports: 12-001-X199400214426Description:
In the MARS Project (Monitoring Agriculture with Remote Sensing) of the E.C. (European Community), area frames based on a square grid are used for area estimation through ground surveys and high resolution satellite images. These satellite images are useful, though expensive, for area estimation: their use for yield estimation is not yet operational. To fill this gap the sample elements (segments) of the area survey are used as well for sampling farms with a template of points overlaid on the segment. Most often we use a fixed number of points per segment. Farmers are asked to provide global data for the farm, and estimates are computed with a Horvitz-Thompson approach. Major problems include locating farmers and checking for misunderstanding of instructions. Good results are obtained for area and for production of the main crops. Area frames need to be complemented with list frames (multiple frames) to give reliable estimates for livestock.
Release date: 1994-12-15 - 7. The creation of a residential address register for coverage improvement in the 1991 Canadian census ArchivedArticles and reports: 12-001-X199200114495Description:
The Address Register is a frame of residential addresses for medium and large urban centres covered by Geography Division’s Area Master File (AMF) at Statistics Canada. For British Columbia, the Address Register was extended to include smaller urban population centres as well as some rural areas. The paper provides an historical overview of the project, its objective as a means of reducing undercoverage in the 1991 Census of Canada, its sources and product, the methodology required for its initial production, the proposed post-censal evaluation and prospects for the future.
Release date: 1992-06-15 - Articles and reports: 12-001-X197800254834Description: Frames designed for continuous surveys are sometimes used for ad hoc surveys which require selection of sampling units separate from those selected for the continuous survey. This paper presents an unbiased extension of Keyfitz’s (1951) sample updating method to the case where a portion of the frame has been reserved for surveys other than the main continuous survey. A simple although biased alternative is presented. The scope under Platek and Singh’s (1975) design strategy for an area based continuous survey requiring updating is then expanded to encompass rotation of first stage units, establishment of a separate special survey sub-frame, and procedures to prevent re-selection of ultimate sampling units. The methods are evaluated in a Monte Carlo study using Census data to simulate the design for the Canadian Labour Force Survey.Release date: 1978-12-15
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- Articles and reports: 12-001-X20060029551Description:
To select a survey sample, it happens that one does not have a frame containing the desired collection units, but rather another frame of units linked in a certain way to the list of collection units. It can then be considered to select a sample from the available frame in order to produce an estimate for the desired target population by using the links existing between the two. This can be designated by Indirect Sampling.
Estimation for the target population surveyed by Indirect Sampling can constitute a big challenge, in particular if the links between the units of the two are not one-to-one. The problem comes especially from the difficulty to associate a selection probability, or an estimation weight, to the surveyed units of the target population. In order to solve this type of estimation problem, the Generalized Weight Share Method (GWSM) has been developed by Lavallée (1995) and Lavallée (2002). The GWSM provides an estimation weight for every surveyed unit of the target population.
This paper first describes Indirect Sampling, which constitutes the foundations of the GWSM. Second, an overview of the GWSM is given where we formulate the GWSM in a theoretical framework using matrix notation. Third, we present some properties of the GWSM such as unbiasedness and transitivity. Fourth, we consider the special case where the links between the two populations are expressed by indicator variables. Fifth, some special typical linkages are studied to assess their impact on the GWSM. Finally, we consider the problem of optimality. We obtain optimal weights in a weak sense (for specific values of the variable of interest), and conditions for which these weights are also optimal in a strong sense and independent of the variable of interest.
Release date: 2006-12-21 - 2. A synthetic, robust and efficient method of making small area population estimates in France ArchivedArticles and reports: 12-001-X19970023620Description:
Since France has no population registers, population censuses are the basis for its socio-demographic information system. However, between two censuses, some data must be updated, in particular at a high level of geographic detail, especially since censuses are tending, for various reasons, to be less frequent. In 1993, the Institut National de la Statistique et des Études Économiques (INSEE) set up a team whose objective was to propose a system to substantially improve the existing mechanism for making small area population estimates. Its task was twofold: to prepare an efficient and robust synthesis of the information available from different administrative sources, and to assemble a sufficient number of "good" sources. The "multi-source" system that it designed, which is reported on here, is flexible and reliable, without being overly complex.
Release date: 1998-03-12 - Articles and reports: 12-001-X199500114411Description:
In 1991, Statistics Canada for the first time adjusted the Population Estimates Program for undercoverage in the 1991 Census. The Census coverage studies provided reliable estimates of undercoverage at the provincial level and for national estimates of large age - sex domains. However, the population series required estimates of undercoverage for age - sex domains within each province and territory. Since the direct survey estimates for some of these small domains had large standard errors due to the small sample size in the domain, small area modelling techniques were needed. In order to incorporate the varying degrees of reliability of the direct survey estimates, a regression model utilizing an Empirical Bayes methodology was used to estimate the undercoverage in small domains. A raking ratio procedure was then applied to the undercoverage estimates to preserve consistency with the marginal direct survey estimates. The results of this modelling process are shown along with the estimated reduction in standard errors.
Release date: 1995-06-15 - Articles and reports: 12-001-X199400214422Description:
Dual system estimation (DSE) has been used since 1950 by the U.S. Bureau of Census for coverage evaluation of the decennial census. In the DSE approach, data from a sample is combined with data from the census to estimate census undercount and overcount. DSE relies upon the assumption that individuals in both the census and the sample can be matched perfectly. The unavoidable mismatches and erroneous nonmatches reduce the accuracy of the DSE. This paper reconsiders the DSE approach by relaxing the perfect matching assumption and proposes models to describe two types of matching errors, false matches of nonmatching cases and false nonmatches of matching cases. Methods for estimating population total and census undercount are presented and illustrated using data from 1986 Los Angeles test census and 1990 Decennial Census.
Release date: 1994-12-15 - Articles and reports: 12-001-X199400214426Description:
In the MARS Project (Monitoring Agriculture with Remote Sensing) of the E.C. (European Community), area frames based on a square grid are used for area estimation through ground surveys and high resolution satellite images. These satellite images are useful, though expensive, for area estimation: their use for yield estimation is not yet operational. To fill this gap the sample elements (segments) of the area survey are used as well for sampling farms with a template of points overlaid on the segment. Most often we use a fixed number of points per segment. Farmers are asked to provide global data for the farm, and estimates are computed with a Horvitz-Thompson approach. Major problems include locating farmers and checking for misunderstanding of instructions. Good results are obtained for area and for production of the main crops. Area frames need to be complemented with list frames (multiple frames) to give reliable estimates for livestock.
Release date: 1994-12-15 - 6. The creation of a residential address register for coverage improvement in the 1991 Canadian census ArchivedArticles and reports: 12-001-X199200114495Description:
The Address Register is a frame of residential addresses for medium and large urban centres covered by Geography Division’s Area Master File (AMF) at Statistics Canada. For British Columbia, the Address Register was extended to include smaller urban population centres as well as some rural areas. The paper provides an historical overview of the project, its objective as a means of reducing undercoverage in the 1991 Census of Canada, its sources and product, the methodology required for its initial production, the proposed post-censal evaluation and prospects for the future.
Release date: 1992-06-15 - Articles and reports: 12-001-X197800254834Description: Frames designed for continuous surveys are sometimes used for ad hoc surveys which require selection of sampling units separate from those selected for the continuous survey. This paper presents an unbiased extension of Keyfitz’s (1951) sample updating method to the case where a portion of the frame has been reserved for surveys other than the main continuous survey. A simple although biased alternative is presented. The scope under Platek and Singh’s (1975) design strategy for an area based continuous survey requiring updating is then expanded to encompass rotation of first stage units, establishment of a separate special survey sub-frame, and procedures to prevent re-selection of ultimate sampling units. The methods are evaluated in a Monte Carlo study using Census data to simulate the design for the Canadian Labour Force Survey.Release date: 1978-12-15
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- 1. Overcoverage in the 2011 Canadian Census ArchivedSurveys and statistical programs – Documentation: 11-522-X201300014269Description:
The Census Overcoverage Study (COS) is a critical post-census coverage measurement study. Its main objective is to produce estimates of the number of people erroneously enumerated, by province and territory, study the characteristics of individuals counted multiple times and identify possible reasons for the errors. The COS is based on the sampling and clerical review of groups of connected records that are built by linking the census response database to an administrative frame, and to itself. In this paper we describe the new 2011 COS methodology. This methodology has incorporated numerous improvements including a greater use of probabilistic record-linkage, the estimation of linking parameters with an Expectation-Maximization (E-M) algorithm, and the efficient use of household information to detect more overcoverage cases.
Release date: 2014-10-31
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