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- Surveys and statistical programs – Documentation: 12-002-X20040027035Description:
As part of the processing of the National Longitudinal Survey of Children and Youth (NLSCY) cycle 4 data, historical revisions have been made to the data of the first 3 cycles, either to correct errors or to update the data. During processing, particular attention was given to the PERSRUK (Person Identifier) and the FIELDRUK (Household Identifier). The same level of attention has not been given to the other identifiers that are included in the data base, the CHILDID (Person identifier) and the _IDHD01 (Household identifier). These identifiers have been created for the public files and can also be found in the master files by default. The PERSRUK should be used to link records between files and the FIELDRUK to determine the household when using the master files.
Release date: 2004-10-05 - Articles and reports: 11-522-X20020016712Description:
In this paper, we consider the effect of the interval censoring of cessation time on intensity parameter estimation with regard to smoking cessation and pregnancy. The three waves of the National Population Health Survey allow the methodology of event history analysis to be applied to smoking initiation, cessation and relapse. One issue of interest is the relationship between smoking cessation and pregnancy. If a longitudinal respondent who is a smoker at the first cycle ceases smoking by the second cycle, we know the cessation time to within an interval of length at most a year, since the respondent is asked for the age at which she stopped smoking, and her date of birth is known. We also know whether she is pregnant at the time of the second cycle, and whether she has given birth since the time of the first cycle. For many such subjects, we know the date of conception to within a relatively small interval. If we knew the time of smoking cessation and pregnancy period exactly for each member who experienced one or other of these events between cycles, we could model their temporal relationship through their joint intensities.
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016713Description:
This paper explores the relationship between low income and prevalence of asthma. The genetic and environmental determinants are incompletely understood. It has been observed in a previous study that Canadians with low incomes are at increased risk of asthma. Based on data from 17,605 subjects 12 years of age or older who participated in the first cycle of the National Population Health Survey (NPHS) from 1994 to 1995, males and females with low incomes had 1.44- and 1.33-fold increases, respectively, in the prevalence of asthma compared with their counterparts with high incomes. However, there was no significant difference observed between middle and high income categories. Therefore, it is not clear if there is a more systematic relationship between income adequacy and asthma occurrence. A much larger sample size of the second cycle of the NPHS allowed us to further explore if the prevalence of asthma increases with decreasing income adequacy among Canadians.
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016714Description:
In this highly technical paper, we illustrate the application of the delete-a-group jack-knife variance estimator approach to a particular complex multi-wave longitudinal study, demonstrating its utility for linear regression and other analytic models. The delete-a-group jack-knife variance estimator is proving a very useful tool for measuring variances under complex sampling designs. This technique divides the first-phase sample into mutually exclusive and nearly equal variance groups, deletes one group at a time to create a set of replicates and makes analogous weighting adjustments in each replicate to those done for the sample as a whole. Variance estimation proceeds in the standard (unstratified) jack-knife fashion.
Our application is to the Chicago Health and Aging Project (CHAP), a community-based longitudinal study examining risk factors for chronic health problems of older adults. A major aim of the study is the investigation of risk factors for incident Alzheimer's disease. The current design of CHAP has two components: (1) Every three years, all surviving members of the cohort are interviewed on a variety of health-related topics. These interviews include cognitive and physical function measures. (2) At each of these waves of data collection, a stratified Poisson sample is drawn from among the respondents to the full population interview for detailed clinical evaluation and neuropsychological testing. To investigate risk factors for incident disease, a 'disease-free' cohort is identified at the preceding time point and forms one major stratum in the sampling frame.
We provide proofs of the theoretical applicability of the delete-a-group jack-knife for particular estimators under this Poisson design, paying needed attention to the distinction between finite-population and infinite-population (model) inference. In addition, we examine the issue of determining the 'right number' of variance groups.
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016743Description:
There is much interest in using data from longitudinal surveys to help understand life history processes such as education, employment, fertility, health and marriage. The analysis of data on the durations of spells or sojourns that individuals spend in certain states (e.g., employment, marriage) is a primary tool in studying such processes. This paper examines methods for analysing duration data that address important features associated with longitudinal surveys: the use of complex survey designs in heterogeneous populations; missing or inaccurate information about the timing of events; and the possibility of non-ignorable dropout or censoring mechanisms. Parametric and non-parametric techniques for estimation and for model checking are considered. Both new and existing methodology are proposed and applied to duration data from Canada's Survey of Labour and Income Dynamics (SLID).
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016744Description:
A developmental trajectory describes the course of a behaviour over age or time. This technical paper provides an overview of a semi-parametric, group-based method for analysing developmental trajectories. This methodology provides an alternative to assuming a homogenous population of trajectories as is done in standard growth modelling.
Four capabilities are described: (1) the capability to identify, rather than assume, distinctive groups of trajectories; (2) the capability to estimate the proportion of the population following each such trajectory group; (3) the capability to relate group membership probability to individual characteristics and circumstances; and (4) the capability to use the group membership probabilities for various other purposes, such as creating profiles of group members.
In addition, two important extensions of the method are described: the capability to add time-varying covariates to trajectory models and the capability to estimate joint trajectory models of distinct but related behaviours. The former provides the statistical capacity for testing if a contemporary factor, such as an experimental intervention or a non-experimental event like pregnancy, deflects a pre-existing trajectory. The latter provides the capability to study the unfolding of distinct but related behaviours such as problematic childhood behaviour and adolescent drug abuse.
Release date: 2004-09-13 - 7. The dynamics of income in four countries ArchivedArticles and reports: 11-522-X20020016747Description:
This project seeks to shed light not only on the degree to which individuals are stuck in the low-income range, but also on those who have sufficient opportunity to move into the upper part of the income distribution. It also seeks to compare patterns of mobility through the income distribution in North America and Europe, shedding light on the impact of different models of integration. Cross-National Equivalent File data from the British Household Panel Survey (BHPS) for the United Kingdom, the German Socio-Economic Panel (GSOEP) for Germany, the Panel Study of Income Dynamics (PSID) for the United States and the Survey of Labour Income Dynamics (SLID) for Canada offer a comparative analysis of the dynamics of household income during the 1990s, paying particular attention to both low- and high-income dynamics. Canadian administrative data drawn from income tax files are also used. These panel datasets range in length from six years (for the SLID) to almost 20 years (for the PSID and the Canadian administrative data). The analysis focuses on developments during the 1990s, but also explores the sensitivity of the results to changes in the length of the period analysed.
The analysis begins by offering a broad descriptive overview of the major characteristics and events (demographic versus labour market) that determine levels and changes in adjusted household incomes. Attention is paid to movements into and out of low- and high- income ranges. A number of definitions are used, incorporating absolute and relative notions of poverty. The sensitivity of the results to the use of various equivalence scales is examined. An overview offers a broad picture of the state of household income in each country and the relative roles of family structure, the labour market and welfare state in determining income mobility. The paper employs discrete time-hazard methods to model the dynamics of entry to and exit from both low and high income.
Both observed and unobserved heterogeneity are controlled for with the intention of highlighting differences in the determinants of the transition rates between the countries. This is done in a way that assesses the importance of the relative roles of family, market and state. Attention is also paid to important institutional changes, most notably the increasing integration of product and labour markets in North America and Europe.
Release date: 2004-09-13 - Articles and reports: 11F0019M2004227Geography: CanadaDescription:
This paper examines trends in earnings, using tax-based longitudinal data from the last two decades and synthetic cohort analysis.
Release date: 2004-08-20 - Articles and reports: 12-001-X20040016998Description:
The Canadian Labour Force Survey (LFS) was not designed to be a longitudinal survey. However, given that respondent households typically remain in the sample for six consecutive months, it is possible to reconstruct six-month fragments of longitudinal data from the monthly records of household members. Such longitudinal micro-data - altogether consisting of millions of person-months of individual and family level data - is useful for analyses of monthly labour market dynamics over relatively long periods of time, 25 years and more.
We make use of these data to estimate hazard functions describing transitions among the labour market states: self-employed, paid employee and not employed. Data on job tenure, for employed respondents, and on the date last worked, for those not employed - together with the date of survey responses - allow the construction of models that include terms reflecting seasonality and macro-economic cycles as well as the duration dependence of each type of transition. In addition, the LFS data permits spouse labour market activity and family composition variables to be included in the hazard models as time-varying covariates. The estimated hazard equations have been incorporated in the LifePaths microsimulation model. In that setting, the equations have been used to simulate lifetime employment activity from past, present and future birth cohorts. Simulation results have been validated by comparison with the age profiles of LFS employment/population ratios for the period 1976 to 2001.
Release date: 2004-07-14 - Surveys and statistical programs – Documentation: 89F0078XDescription:
The National Longitudinal Survey of Children and Youth (NLSCY) is the first Canada-wide survey of children. Starting in 1994, it will gather information on a sample of children and their life experiences. It will follow these children over time. The survey will collect information on children and their families, education, health, development, behaviour, friends, activities, etc. This document describes the survey instruments of cycle 4.
Release date: 2004-07-02
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- Articles and reports: 11-522-X20020016712Description:
In this paper, we consider the effect of the interval censoring of cessation time on intensity parameter estimation with regard to smoking cessation and pregnancy. The three waves of the National Population Health Survey allow the methodology of event history analysis to be applied to smoking initiation, cessation and relapse. One issue of interest is the relationship between smoking cessation and pregnancy. If a longitudinal respondent who is a smoker at the first cycle ceases smoking by the second cycle, we know the cessation time to within an interval of length at most a year, since the respondent is asked for the age at which she stopped smoking, and her date of birth is known. We also know whether she is pregnant at the time of the second cycle, and whether she has given birth since the time of the first cycle. For many such subjects, we know the date of conception to within a relatively small interval. If we knew the time of smoking cessation and pregnancy period exactly for each member who experienced one or other of these events between cycles, we could model their temporal relationship through their joint intensities.
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016713Description:
This paper explores the relationship between low income and prevalence of asthma. The genetic and environmental determinants are incompletely understood. It has been observed in a previous study that Canadians with low incomes are at increased risk of asthma. Based on data from 17,605 subjects 12 years of age or older who participated in the first cycle of the National Population Health Survey (NPHS) from 1994 to 1995, males and females with low incomes had 1.44- and 1.33-fold increases, respectively, in the prevalence of asthma compared with their counterparts with high incomes. However, there was no significant difference observed between middle and high income categories. Therefore, it is not clear if there is a more systematic relationship between income adequacy and asthma occurrence. A much larger sample size of the second cycle of the NPHS allowed us to further explore if the prevalence of asthma increases with decreasing income adequacy among Canadians.
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016714Description:
In this highly technical paper, we illustrate the application of the delete-a-group jack-knife variance estimator approach to a particular complex multi-wave longitudinal study, demonstrating its utility for linear regression and other analytic models. The delete-a-group jack-knife variance estimator is proving a very useful tool for measuring variances under complex sampling designs. This technique divides the first-phase sample into mutually exclusive and nearly equal variance groups, deletes one group at a time to create a set of replicates and makes analogous weighting adjustments in each replicate to those done for the sample as a whole. Variance estimation proceeds in the standard (unstratified) jack-knife fashion.
Our application is to the Chicago Health and Aging Project (CHAP), a community-based longitudinal study examining risk factors for chronic health problems of older adults. A major aim of the study is the investigation of risk factors for incident Alzheimer's disease. The current design of CHAP has two components: (1) Every three years, all surviving members of the cohort are interviewed on a variety of health-related topics. These interviews include cognitive and physical function measures. (2) At each of these waves of data collection, a stratified Poisson sample is drawn from among the respondents to the full population interview for detailed clinical evaluation and neuropsychological testing. To investigate risk factors for incident disease, a 'disease-free' cohort is identified at the preceding time point and forms one major stratum in the sampling frame.
We provide proofs of the theoretical applicability of the delete-a-group jack-knife for particular estimators under this Poisson design, paying needed attention to the distinction between finite-population and infinite-population (model) inference. In addition, we examine the issue of determining the 'right number' of variance groups.
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016743Description:
There is much interest in using data from longitudinal surveys to help understand life history processes such as education, employment, fertility, health and marriage. The analysis of data on the durations of spells or sojourns that individuals spend in certain states (e.g., employment, marriage) is a primary tool in studying such processes. This paper examines methods for analysing duration data that address important features associated with longitudinal surveys: the use of complex survey designs in heterogeneous populations; missing or inaccurate information about the timing of events; and the possibility of non-ignorable dropout or censoring mechanisms. Parametric and non-parametric techniques for estimation and for model checking are considered. Both new and existing methodology are proposed and applied to duration data from Canada's Survey of Labour and Income Dynamics (SLID).
Release date: 2004-09-13 - Articles and reports: 11-522-X20020016744Description:
A developmental trajectory describes the course of a behaviour over age or time. This technical paper provides an overview of a semi-parametric, group-based method for analysing developmental trajectories. This methodology provides an alternative to assuming a homogenous population of trajectories as is done in standard growth modelling.
Four capabilities are described: (1) the capability to identify, rather than assume, distinctive groups of trajectories; (2) the capability to estimate the proportion of the population following each such trajectory group; (3) the capability to relate group membership probability to individual characteristics and circumstances; and (4) the capability to use the group membership probabilities for various other purposes, such as creating profiles of group members.
In addition, two important extensions of the method are described: the capability to add time-varying covariates to trajectory models and the capability to estimate joint trajectory models of distinct but related behaviours. The former provides the statistical capacity for testing if a contemporary factor, such as an experimental intervention or a non-experimental event like pregnancy, deflects a pre-existing trajectory. The latter provides the capability to study the unfolding of distinct but related behaviours such as problematic childhood behaviour and adolescent drug abuse.
Release date: 2004-09-13 - 6. The dynamics of income in four countries ArchivedArticles and reports: 11-522-X20020016747Description:
This project seeks to shed light not only on the degree to which individuals are stuck in the low-income range, but also on those who have sufficient opportunity to move into the upper part of the income distribution. It also seeks to compare patterns of mobility through the income distribution in North America and Europe, shedding light on the impact of different models of integration. Cross-National Equivalent File data from the British Household Panel Survey (BHPS) for the United Kingdom, the German Socio-Economic Panel (GSOEP) for Germany, the Panel Study of Income Dynamics (PSID) for the United States and the Survey of Labour Income Dynamics (SLID) for Canada offer a comparative analysis of the dynamics of household income during the 1990s, paying particular attention to both low- and high-income dynamics. Canadian administrative data drawn from income tax files are also used. These panel datasets range in length from six years (for the SLID) to almost 20 years (for the PSID and the Canadian administrative data). The analysis focuses on developments during the 1990s, but also explores the sensitivity of the results to changes in the length of the period analysed.
The analysis begins by offering a broad descriptive overview of the major characteristics and events (demographic versus labour market) that determine levels and changes in adjusted household incomes. Attention is paid to movements into and out of low- and high- income ranges. A number of definitions are used, incorporating absolute and relative notions of poverty. The sensitivity of the results to the use of various equivalence scales is examined. An overview offers a broad picture of the state of household income in each country and the relative roles of family structure, the labour market and welfare state in determining income mobility. The paper employs discrete time-hazard methods to model the dynamics of entry to and exit from both low and high income.
Both observed and unobserved heterogeneity are controlled for with the intention of highlighting differences in the determinants of the transition rates between the countries. This is done in a way that assesses the importance of the relative roles of family, market and state. Attention is also paid to important institutional changes, most notably the increasing integration of product and labour markets in North America and Europe.
Release date: 2004-09-13 - Articles and reports: 11F0019M2004227Geography: CanadaDescription:
This paper examines trends in earnings, using tax-based longitudinal data from the last two decades and synthetic cohort analysis.
Release date: 2004-08-20 - Articles and reports: 12-001-X20040016998Description:
The Canadian Labour Force Survey (LFS) was not designed to be a longitudinal survey. However, given that respondent households typically remain in the sample for six consecutive months, it is possible to reconstruct six-month fragments of longitudinal data from the monthly records of household members. Such longitudinal micro-data - altogether consisting of millions of person-months of individual and family level data - is useful for analyses of monthly labour market dynamics over relatively long periods of time, 25 years and more.
We make use of these data to estimate hazard functions describing transitions among the labour market states: self-employed, paid employee and not employed. Data on job tenure, for employed respondents, and on the date last worked, for those not employed - together with the date of survey responses - allow the construction of models that include terms reflecting seasonality and macro-economic cycles as well as the duration dependence of each type of transition. In addition, the LFS data permits spouse labour market activity and family composition variables to be included in the hazard models as time-varying covariates. The estimated hazard equations have been incorporated in the LifePaths microsimulation model. In that setting, the equations have been used to simulate lifetime employment activity from past, present and future birth cohorts. Simulation results have been validated by comparison with the age profiles of LFS employment/population ratios for the period 1976 to 2001.
Release date: 2004-07-14 - Articles and reports: 12-002-X20040016904Description:
This article provides a practical example of the development of a survival analysis model. It begins with an overview of the software tool that was used, SAS. The next section examines the construction of a longitudinal file and the challenges that may present. Of particular interest are explanatory variables that do not have a constant value over time. An example of a practical application is provided to illustrate the survival approach. The example consists of an analysis based on data from the Survey of Labour and Income Dynamics (SLID), specifically data from panel 1 between January 1993 and December 1998. Survey information in vector form is used to develop a Cox semi-parametric model. Comments are provided on a sample computer program. The way in which the program handles the main variables is also discussed. The last section contains a brief description of the results of a relatively simple model.
Release date: 2004-04-15 - 10. Producing efficient data files using Stat/Transfer ArchivedArticles and reports: 12-002-X20040016905Description:
Large data sets present several challenges to researchers, particularly to less experienced researchers. One of the most time-consuming and frustrating activities for beginning researchers, who do not have experience with large datasets, can be pruning or parsing the data set to only the variables and sample of interest. The production of an 'efficient' data file can assist in the increased performance of hardware and software as well as reducing frustration for the researcher. One way of producing a parsed efficient data file using a program called Stat/Transfer is presented.
Release date: 2004-04-15
Reference (3)
Reference (3) ((3 results))
- Surveys and statistical programs – Documentation: 12-002-X20040027035Description:
As part of the processing of the National Longitudinal Survey of Children and Youth (NLSCY) cycle 4 data, historical revisions have been made to the data of the first 3 cycles, either to correct errors or to update the data. During processing, particular attention was given to the PERSRUK (Person Identifier) and the FIELDRUK (Household Identifier). The same level of attention has not been given to the other identifiers that are included in the data base, the CHILDID (Person identifier) and the _IDHD01 (Household identifier). These identifiers have been created for the public files and can also be found in the master files by default. The PERSRUK should be used to link records between files and the FIELDRUK to determine the household when using the master files.
Release date: 2004-10-05 - Surveys and statistical programs – Documentation: 89F0078XDescription:
The National Longitudinal Survey of Children and Youth (NLSCY) is the first Canada-wide survey of children. Starting in 1994, it will gather information on a sample of children and their life experiences. It will follow these children over time. The survey will collect information on children and their families, education, health, development, behaviour, friends, activities, etc. This document describes the survey instruments of cycle 4.
Release date: 2004-07-02 - Surveys and statistical programs – Documentation: 89-612-XDescription:
This paper describes the structure and linkage of two databases: the Longitudinal Administrative Databank (LAD), and the Longitudinal Immigration Database (IMDB). The combined data associate landed immigrant taxfilers on the LAD with their key characteristics upon immigration. The paper highlights how the combined information, referred to here as the LAD_IMDB, enhances and complements the existing separate databases. The paper compares the full IMDB file with the sample of immigrants to assess the representativeness of the sample file.
Release date: 2004-01-05
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