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- Articles and reports: 12-001-X200800210756Description:
In longitudinal surveys nonresponse often occurs in a pattern that is not monotone. We consider estimation of time-dependent means under the assumption that the nonresponse mechanism is last-value-dependent. Since the last value itself may be missing when nonresponse is nonmonotone, the nonresponse mechanism under consideration is nonignorable. We propose an imputation method by first deriving some regression imputation models according to the nonresponse mechanism and then applying nonparametric regression imputation. We assume that the longitudinal data follow a Markov chain with finite second-order moments. No other assumption is imposed on the joint distribution of longitudinal data and their nonresponse indicators. A bootstrap method is applied for variance estimation. Some simulation results and an example concerning the Current Employment Survey are presented.
Release date: 2008-12-23 - Articles and reports: 75F0002M1992009Description:
There are many issues to consider when developing and conducting a survey. Length, complexity and timing of the survey are all factors that may influence potential respondents' likelihood to participate in a survey. One important issue that affects this decision is the extent to which a questionnaire appears to be an invasion of privacy. Information on income and finances is one type of information that many people are reluctant to share but that is important for policy and research purposes.
Collecting such information for the Survey of Consumer Finances (SCF) has proven difficult, and has resulted in higher than average non-response rate for a supplemental survey to the Labour Force Survey. Given the similarity between the SCF and an upcoming survey, the Survey of Labour and Income Dynamics (SLID), it is important to examine the reasons behind the SCF's higher non-response rate and obtain suggestions for increasing response rate and gaining commitment from respondents to the 6-year SLID.
Statistics Canada asked Price Waterhouse to conduct focus groups and in-depth interviews with respondents and non-respondents to the SCF. The objectives of these focus groups and in-depth interviews were to explore reasons for response and non-response, issues of privacy and confidentiality and understanding of the terms used in the survey, and to test reactions to the appearance of a draft SLID package.
Release date: 2008-10-21 - Articles and reports: 82-622-X2008001Geography: CanadaDescription:
In this study, I examine the factorial validity of selected modules from the Canadian Survey of Experiences with Primary Health Care (CSE-PHC), in order to determine the potential for combining the items within each module into summary indices representing global primary health care concepts. The modules examined were: Patient Assessment of Chronic Illness Care (PACIC), Patient Activation (PA), Managing Own Health Care (MOHC), and Confidence in the Health Care System (CHCS). Confirmatory factor analyses were conducted on each module to assess the degree to which multiple observed items reflected the presence of common latent factors. While a four-factor model was initially specified for the PACIC instrument on the basis of priory theory and research, it did not fit the data well; rather, a revised two-factor model was found to be most appropriate. These two factors were labelled: "Whole Person Care" and "Coordination of Care". The remaining modules studied here (i.e., PA, MOHC, and CHCS) were all well-represented by single-factor models. The results suggest that the original factor structure of the PACIC developed within studies using clinical samples does not hold in general populations, although the precise reasons for this are not clear. Further empirical investigation will be required to shed more light on this discrepancy. The two factors identified here for the PACIC, as well as the single factors produced for the PA, MOHC, and CHCS could be used as the basis of summary indices for use in further analyses with the CSE-PHC.
Release date: 2008-07-08 - 4. A Bayesian allocation of undecided voters ArchivedArticles and reports: 12-001-X200800110606Description:
Data from election polls in the US are typically presented in two-way categorical tables, and there are many polls before the actual election in November. For example, in the Buckeye State Poll in 1998 for governor there are three polls, January, April and October; the first category represents the candidates (e.g., Fisher, Taft and other) and the second category represents the current status of the voters (likely to vote and not likely to vote for governor of Ohio). There is a substantial number of undecided voters for one or both categories in all three polls, and we use a Bayesian method to allocate the undecided voters to the three candidates. This method permits modeling different patterns of missingness under ignorable and nonignorable assumptions, and a multinomial-Dirichlet model is used to estimate the cell probabilities which can help to predict the winner. We propose a time-dependent nonignorable nonresponse model for the three tables. Here, a nonignorable nonresponse model is centered on an ignorable nonresponse model to induce some flexibility and uncertainty about ignorabilty or nonignorability. As competitors we also consider two other models, an ignorable and a nonignorable nonresponse model. These latter two models assume a common stochastic process to borrow strength over time. Markov chain Monte Carlo methods are used to fit the models. We also construct a parameter that can potentially be used to predict the winner among the candidates in the November election.
Release date: 2008-06-26 - 5. Respondent incentives in a multi-mode panel survey: Cumulative effects on nonresponse and bias ArchivedArticles and reports: 12-001-X200800110607Description:
Respondent incentives are increasingly used as a measure of combating falling response rates and resulting risks of nonresponse bias. Nonresponse in panel surveys is particularly problematic, since even low wave-on-wave nonresponse rates can lead to substantial cumulative losses; if nonresponse is differential, this may lead to increasing bias across waves. Although the effects of incentives have been studied extensively in cross-sectional contexts, little is known about cumulative effects across waves of a panel. We provide new evidence about the effects of continued incentive payments on attrition, bias and item nonresponse, using data from a large scale, multi-wave, mixed mode incentive experiment on a UK government panel survey of young people. In this study, incentives significantly reduced attrition, far outweighing negative effects on item response rates in terms of the amount of information collected by the survey per issued case. Incentives had proportionate effects on retention rates across a range of respondent characteristics and as a result did not reduce attrition bias in terms of those characteristics. The effects of incentives on retention rates were larger for unconditional than conditional incentives and larger in postal than telephone mode. Across waves, the effects on attrition decreased somewhat, although the effects on item nonresponse and the lack of effect on bias remained constant. The effects of incentives at later waves appeared to be independent of incentive treatments and mode of data collection at earlier waves.
Release date: 2008-06-26 - Articles and reports: 12-001-X200800110616Description:
With complete multivariate data the BACON algorithm (Billor, Hadi and Vellemann 2000) yields a robust estimate of the covariance matrix. The corresponding Mahalanobis distance may be used for multivariate outlier detection. When items are missing the EM algorithm is a convenient way to estimate the covariance matrix at each iteration step of the BACON algorithm. In finite population sampling the EM algorithm must be enhanced to estimate the covariance matrix of the population rather than of the sample. A version of the EM algorithm for survey data following a multivariate normal model, the EEM algorithm (Estimated Expectation Maximization), is proposed. The combination of the two algorithms, the BACON-EEM algorithm, is applied to two datasets and compared with alternative methods.
Release date: 2008-06-26 - 7. Impact of telephone versus face to face repeat 24-hour recall interviews on food and nutrition surveys ArchivedArticles and reports: 11-522-X200600110422Description:
Many population surveys collecting food consumption data use 24 hour recall methodology to capture detailed one day intakes. In order to estimate longer term intakes of foods and nutrients from these data, methods have been developed that required a repeat recall to be collected from at least a subset of responders in order to estimate day to day variability. During the Canadian Community Health Survey Cycle 2.2 Nutrition Focus Survey, most first interviews were collected in person and most repeat interviews were conducted by telephone. This paper looks at the impact of the mode of interview on the reported foods and nutrients on both the first day and the repeat day and on the estimation of intra individual variability between the first and the second interviews.
Release date: 2008-03-17 - 8. Discussion and presentation of the disability test results from the Current Population Survey ArchivedArticles and reports: 11-522-X200600110438Description:
In accordance with an effort to design a set of questions for the Current Population Survey (CPS) to measure disability, potential questions were drawn from existing surveys, cognitively and field tested. Based on an analysis of the test data, a set of seven questions was identified, cognitively tested, and placed in the February 2006 CPS for testing. Analysis of the data revealed a lower overall disability rate as measured in the CPS than in the field test, with lower positive response rates for each question. The data did not indicate that there was an adverse effect on the response rates.
Release date: 2008-03-17 - Articles and reports: 11-522-X200600110450Description:
Using survey and contact attempt history data collected with the 2005 National Health Interview Survey (NHIS), a multi-purpose health survey conducted by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC), we set out to explore the impact of participant concerns/reluctance on data quality, as measured by rates of partially complete interviews and item nonresponse. Overall, results show that respondents from households where some type of concern or reluctance (e.g., "too busy," "not interested") was expressed produced higher rates of partially complete interviews and item nonresponse than respondents from households where concern/reluctance was not expressed. Differences by type of concern were also identified.
Release date: 2008-03-17 - 10. The impact of unconditional incentives upon a multi-stage survey: the Health Survey for England ArchivedArticles and reports: 11-522-X200600110451Description:
Household response rates have steadily declined across many large scale social surveys. The Health Survey for England has observed a 9 percentage points decline in response across an eleven year period. Evidence from other studies has suggested that unconditional gifts or incentives, with small monetary value, can improve rates of co-operation. An incentive experiment conducted on the Health Survey for England aimed to replicate findings of a previous experiment carried out on the Family Resources Study, which showed significant increases in household response among those who had received a book of first class stamps with the advance letter. The HSE incentive experiment, however, did not show any significant differences in household response rates, response to other stages of the survey or in respondent profile between two experimental conditions (stamps included with the advance letter, bookmark sent with the advance letter) and the control group (the advance letter alone).
Release date: 2008-03-17
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Analysis (12)
Analysis (12) (0 to 10 of 12 results)
- Articles and reports: 12-001-X200800210756Description:
In longitudinal surveys nonresponse often occurs in a pattern that is not monotone. We consider estimation of time-dependent means under the assumption that the nonresponse mechanism is last-value-dependent. Since the last value itself may be missing when nonresponse is nonmonotone, the nonresponse mechanism under consideration is nonignorable. We propose an imputation method by first deriving some regression imputation models according to the nonresponse mechanism and then applying nonparametric regression imputation. We assume that the longitudinal data follow a Markov chain with finite second-order moments. No other assumption is imposed on the joint distribution of longitudinal data and their nonresponse indicators. A bootstrap method is applied for variance estimation. Some simulation results and an example concerning the Current Employment Survey are presented.
Release date: 2008-12-23 - Articles and reports: 75F0002M1992009Description:
There are many issues to consider when developing and conducting a survey. Length, complexity and timing of the survey are all factors that may influence potential respondents' likelihood to participate in a survey. One important issue that affects this decision is the extent to which a questionnaire appears to be an invasion of privacy. Information on income and finances is one type of information that many people are reluctant to share but that is important for policy and research purposes.
Collecting such information for the Survey of Consumer Finances (SCF) has proven difficult, and has resulted in higher than average non-response rate for a supplemental survey to the Labour Force Survey. Given the similarity between the SCF and an upcoming survey, the Survey of Labour and Income Dynamics (SLID), it is important to examine the reasons behind the SCF's higher non-response rate and obtain suggestions for increasing response rate and gaining commitment from respondents to the 6-year SLID.
Statistics Canada asked Price Waterhouse to conduct focus groups and in-depth interviews with respondents and non-respondents to the SCF. The objectives of these focus groups and in-depth interviews were to explore reasons for response and non-response, issues of privacy and confidentiality and understanding of the terms used in the survey, and to test reactions to the appearance of a draft SLID package.
Release date: 2008-10-21 - Articles and reports: 82-622-X2008001Geography: CanadaDescription:
In this study, I examine the factorial validity of selected modules from the Canadian Survey of Experiences with Primary Health Care (CSE-PHC), in order to determine the potential for combining the items within each module into summary indices representing global primary health care concepts. The modules examined were: Patient Assessment of Chronic Illness Care (PACIC), Patient Activation (PA), Managing Own Health Care (MOHC), and Confidence in the Health Care System (CHCS). Confirmatory factor analyses were conducted on each module to assess the degree to which multiple observed items reflected the presence of common latent factors. While a four-factor model was initially specified for the PACIC instrument on the basis of priory theory and research, it did not fit the data well; rather, a revised two-factor model was found to be most appropriate. These two factors were labelled: "Whole Person Care" and "Coordination of Care". The remaining modules studied here (i.e., PA, MOHC, and CHCS) were all well-represented by single-factor models. The results suggest that the original factor structure of the PACIC developed within studies using clinical samples does not hold in general populations, although the precise reasons for this are not clear. Further empirical investigation will be required to shed more light on this discrepancy. The two factors identified here for the PACIC, as well as the single factors produced for the PA, MOHC, and CHCS could be used as the basis of summary indices for use in further analyses with the CSE-PHC.
Release date: 2008-07-08 - 4. A Bayesian allocation of undecided voters ArchivedArticles and reports: 12-001-X200800110606Description:
Data from election polls in the US are typically presented in two-way categorical tables, and there are many polls before the actual election in November. For example, in the Buckeye State Poll in 1998 for governor there are three polls, January, April and October; the first category represents the candidates (e.g., Fisher, Taft and other) and the second category represents the current status of the voters (likely to vote and not likely to vote for governor of Ohio). There is a substantial number of undecided voters for one or both categories in all three polls, and we use a Bayesian method to allocate the undecided voters to the three candidates. This method permits modeling different patterns of missingness under ignorable and nonignorable assumptions, and a multinomial-Dirichlet model is used to estimate the cell probabilities which can help to predict the winner. We propose a time-dependent nonignorable nonresponse model for the three tables. Here, a nonignorable nonresponse model is centered on an ignorable nonresponse model to induce some flexibility and uncertainty about ignorabilty or nonignorability. As competitors we also consider two other models, an ignorable and a nonignorable nonresponse model. These latter two models assume a common stochastic process to borrow strength over time. Markov chain Monte Carlo methods are used to fit the models. We also construct a parameter that can potentially be used to predict the winner among the candidates in the November election.
Release date: 2008-06-26 - 5. Respondent incentives in a multi-mode panel survey: Cumulative effects on nonresponse and bias ArchivedArticles and reports: 12-001-X200800110607Description:
Respondent incentives are increasingly used as a measure of combating falling response rates and resulting risks of nonresponse bias. Nonresponse in panel surveys is particularly problematic, since even low wave-on-wave nonresponse rates can lead to substantial cumulative losses; if nonresponse is differential, this may lead to increasing bias across waves. Although the effects of incentives have been studied extensively in cross-sectional contexts, little is known about cumulative effects across waves of a panel. We provide new evidence about the effects of continued incentive payments on attrition, bias and item nonresponse, using data from a large scale, multi-wave, mixed mode incentive experiment on a UK government panel survey of young people. In this study, incentives significantly reduced attrition, far outweighing negative effects on item response rates in terms of the amount of information collected by the survey per issued case. Incentives had proportionate effects on retention rates across a range of respondent characteristics and as a result did not reduce attrition bias in terms of those characteristics. The effects of incentives on retention rates were larger for unconditional than conditional incentives and larger in postal than telephone mode. Across waves, the effects on attrition decreased somewhat, although the effects on item nonresponse and the lack of effect on bias remained constant. The effects of incentives at later waves appeared to be independent of incentive treatments and mode of data collection at earlier waves.
Release date: 2008-06-26 - Articles and reports: 12-001-X200800110616Description:
With complete multivariate data the BACON algorithm (Billor, Hadi and Vellemann 2000) yields a robust estimate of the covariance matrix. The corresponding Mahalanobis distance may be used for multivariate outlier detection. When items are missing the EM algorithm is a convenient way to estimate the covariance matrix at each iteration step of the BACON algorithm. In finite population sampling the EM algorithm must be enhanced to estimate the covariance matrix of the population rather than of the sample. A version of the EM algorithm for survey data following a multivariate normal model, the EEM algorithm (Estimated Expectation Maximization), is proposed. The combination of the two algorithms, the BACON-EEM algorithm, is applied to two datasets and compared with alternative methods.
Release date: 2008-06-26 - 7. Impact of telephone versus face to face repeat 24-hour recall interviews on food and nutrition surveys ArchivedArticles and reports: 11-522-X200600110422Description:
Many population surveys collecting food consumption data use 24 hour recall methodology to capture detailed one day intakes. In order to estimate longer term intakes of foods and nutrients from these data, methods have been developed that required a repeat recall to be collected from at least a subset of responders in order to estimate day to day variability. During the Canadian Community Health Survey Cycle 2.2 Nutrition Focus Survey, most first interviews were collected in person and most repeat interviews were conducted by telephone. This paper looks at the impact of the mode of interview on the reported foods and nutrients on both the first day and the repeat day and on the estimation of intra individual variability between the first and the second interviews.
Release date: 2008-03-17 - 8. Discussion and presentation of the disability test results from the Current Population Survey ArchivedArticles and reports: 11-522-X200600110438Description:
In accordance with an effort to design a set of questions for the Current Population Survey (CPS) to measure disability, potential questions were drawn from existing surveys, cognitively and field tested. Based on an analysis of the test data, a set of seven questions was identified, cognitively tested, and placed in the February 2006 CPS for testing. Analysis of the data revealed a lower overall disability rate as measured in the CPS than in the field test, with lower positive response rates for each question. The data did not indicate that there was an adverse effect on the response rates.
Release date: 2008-03-17 - Articles and reports: 11-522-X200600110450Description:
Using survey and contact attempt history data collected with the 2005 National Health Interview Survey (NHIS), a multi-purpose health survey conducted by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC), we set out to explore the impact of participant concerns/reluctance on data quality, as measured by rates of partially complete interviews and item nonresponse. Overall, results show that respondents from households where some type of concern or reluctance (e.g., "too busy," "not interested") was expressed produced higher rates of partially complete interviews and item nonresponse than respondents from households where concern/reluctance was not expressed. Differences by type of concern were also identified.
Release date: 2008-03-17 - 10. The impact of unconditional incentives upon a multi-stage survey: the Health Survey for England ArchivedArticles and reports: 11-522-X200600110451Description:
Household response rates have steadily declined across many large scale social surveys. The Health Survey for England has observed a 9 percentage points decline in response across an eleven year period. Evidence from other studies has suggested that unconditional gifts or incentives, with small monetary value, can improve rates of co-operation. An incentive experiment conducted on the Health Survey for England aimed to replicate findings of a previous experiment carried out on the Family Resources Study, which showed significant increases in household response among those who had received a book of first class stamps with the advance letter. The HSE incentive experiment, however, did not show any significant differences in household response rates, response to other stages of the survey or in respondent profile between two experimental conditions (stamps included with the advance letter, bookmark sent with the advance letter) and the control group (the advance letter alone).
Release date: 2008-03-17
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