Series title: National Longitudinal Survey of Children and Youth
File type: Microdata | File size: 24080 kb | Number of variables: 742 | Number of cases: 22831
Access restrictions: DLI
Survey Date(s): 1994-1995
Topics: Children and youth / Education, training and learning
Geographic Coverage: Canada
The National Longitudinal Survey of Children and Youth (NLSCY) is a long-term research program (started in 1994) that will track a large sample of children over many years, enabling researchers to monitor children's well-being and development.
The National Longitudinal Survey of Children and Youth (NLSCY) is a long-term survey designed to measure child development and well-being. The first cycle of the survey was conducted by Statistics Canada in 1994-1995 on behalf of Human Resources Development Canada. This manual has been produced to facilitate the manipulation of the microdata file and to document data quality and other analytical issues regarding the NLSCY.
It should be pointed out that not all the data collected in the first cycle of the NLSCY are included in this first microdata file. The amount of information collected was so extensive a decision was made to have two releases rather than waiting for all of the data to be processed. The second release will be in 1997. The notable sections to be included in this second release are health variables for the child and the parents, the custody history of the child, and data collected from the teacher and the principal. A complete list of the sections included in the first and second release can be found in Appendix 1 of the printed codebook.
Any questions about the data set or its use should be directed to:
At Statistics Canada:
Michael Sivyer Gilles Montigny
Manager, Dissemination and User Support Project Manager - NLSCY
Special Surveys Division Special Surveys Division
Statistics Canada Statistics Canada
5(B6) Jean Talon Building 5(B6) Jean Talon Building
Tunney's Pasture Tunney's Pasture
Ottawa, Ontario K1A 0T6 Ottawa, Ontario K1A 0T6
Telephone:(613) 951-4598 Telephone:(613) 951-9731
Facsimile:(613) 951-0562 Facsimile:(613) 951-0562
Internet: sivyer@statcan.ca Internet: montgil@statcan.ca
Toll free #: 1-800-461-9050
At Human Resources Development Canada:
Susan McKellar
NLSCY Project Coordinator
Applied Research Branch
Human Resources Development Canada
Place du Portage - Phase IV, Mailbox 528
Hull, Quebec K1A 0J9
Telephone:(819) 953-4230
Facsimile:(819) 994-2480
Internet: susan.mckellar@spg.org
2.0 Background
Before the NLSCY was undertaken there were few statistical studies describing a broad range of characteristics of children in Canada. Measures of health, well-being and life opportunities are needed, however, if governments and researchers hope to learn more about the ongoing life conditions of Canadian children and youth, and their developmental experiences. Longitudinal data are central to discovering developmental changes occurring in children over time, and studying the impacts of the social environment of the child and various family-related factors.
Data on the prevalence of, and interaction among, various characteristics and conditions will assist policy makers in understanding the processes that modify risk and protect and encourage the healthy development of children. Such information will enhance the capacity of the various partners in society to develop effective strategies, policies and programs to help children succeed in our changing society.
3.0 Objectives
The primary objective of the NLSCY is to develop a national database on the characteristics and life experiences of children and youth in Canada as they grow from infancy to adulthood. The more specific objectives of the NLSCY are:
- to determine the prevalence of various biological, social and economic characteristics and risk factors of children and youth in Canada;
- to monitor the impact of such risk factors, life events and protective factors on the development of these children; and
- to provide this information to policy and program officials for use in developing effective policies and strategies to help young people live healthy, active and rewarding lives.
Underlying these objectives is the need to: - fill an existing information gap regarding the characteristics and experiences of children in Canada, particularly in their early years;
- focus on all aspects of the child in a holistic manner (i.e., the child, his/her family, school, and community);
- provide national, and as far as possible, provincial-level data; and
- explore subject areas that are amenable to policy intervention and which affect a significant segment of the population.
4.0 Survey Methodology
The requirement for the NLSCY design was to select a representative sample of children in Canada and to follow and monitor these children over time into adulthood.
4.1 Definition of the NLSCY Population
The target population of the NLSCY for Cycle 1 consisted of Canadian children aged newborn to 11 years of age. There were some exclusions made for operational reasons which are discussed further in this section.
4.2 NLSCY Sample Design
In terms of sampling, the starting point for the NLSCY design was the household. Sampled households actually came from three possible sources which have been labelled as the Main Component, the Integrated Component and the Territories Component.
4.2.1 The Main Component
For Cycle 1 of the NLSCY the requirement was to select households with children, specifically children 0 to 11 years of age. The problem is that the majority of households do not contain children in this age range. In fact approximately only 26% of Canadian households in the 10 provinces contain at least one child in the 0 to 11 age range. A method had to be found to facilitate finding households likely to contain children, otherwise precious dollars would have had to be spent screening households in order to identify those with children. The answer was found with Statistics Canada's Labour Force Survey (LFS).
The Labour Force Survey is conducted on a monthly basis and collects basic demographic information about all household members of a representative sample of Canadian households as well as labour market information about the adults living in these households. For the NLSCY households that were currently or had recently been in the LFS sample were examined to determine which had children. This served as the basis of the household sample for the NLSCY Main Component. Approximately 12,900 households were selected for the sample for the NLSCY Main Component.
It should be mentioned that the LFS excludes certain populations since they are not part of the LFS sample frame, specifically individuals living in the Yukon or Northwest Territories, individuals living in institutions, and finally individuals living on Indian Reserves. In order to compensate for the first exclusion (i.e., the Yukon and Northwest Territories) the NLSCY introduced the Territories Component as described below. The undercoverage that resulted for the other exclusions (institutions and Indian Reserves) represents approximately 0.5% of children 0 to 11 years of age living in the 10 provinces.
4.2.2 The Integrated Component (NPHS)
At the same time that the NLSCY was being designed there was another national longitudinal survey being launched by Statistics Canada; namely the National Population Health Survey (NPHS). Its purpose is to produce estimates of physical and mental health of Canadians and to identify the factors that determine good and ill health.
Because both the NLSCY and the NPHS needed to collect data on the health of Canadian children, it was decided that a portion of the sample and content of the two surveys would be integrated for the 10 provinces. The children selected by the NPHS were part of the sample for both surveys.
The household sample for the Integrated Component was selected in a manner very similar to what was used for the Main Component; it was based on the Labour Force Survey frame. However it was a fresh sample that was selected specifically for the NPHS as opposed to households already participating in the Labour Force Survey. The way that this plan was implemented for Cycle 1 was that for a certain portion of the NPHS household sample, a random selection of one person in the household was made, with no restriction on age; i.e., everyone in the household, including children, had an equal chance of being selected. If this selected person was a child aged 0 to 11, then this household was considered to be part of the Integrated sample and the NLSCY interview was administered to that household; otherwise the NPHS was conducted. There were approximately 2,700 NLSCY households selected for the Integrated Component.
The exclusions that were discussed above for the Main Component (the Yukon, Northwest Territories, institutions and Indian Reserves) also apply to the NPHS Component.
4.2.3 The Territories Component
The household sample for the Main and the Integrated Components were both based on the Labour Force sample frame which excludes the Yukon and Northwest Territories (NWT). However there was a requirement to have estimates for the north for both the NLSCY and the NPHS. Therefore the Territories Component was introduced which again was an integrated sample for both NLSCY and NPHS. The sample for the Territories Component was drawn from the population of private occupied dwellings. The Yukon sample excludes institutions and unorganized areas. The NWT sample has the same exclusions as well as very remote areas and very small communities.
In terms of implementation for the territories sample, if there was a least one child 0 to 11 in any of the selected dwellings, then the NLSCY was conducted for this dwelling. The goal for Cycle 1 was to produce a sample that would yield data for approximately 2,300 children living in each of the Yukon and NWT.
The Territories Component is somewhat different than the other components in that it is fully integrated with NPHS. For households with children the NLSCY was administered for children living in the household and as well one person was selected at random in each household for the NPHS. For Cycle 1, if that person was 12 years of age or older the NPHS was administered. As such, it was necessary to cut down on the content of both surveys in order to reduce respondent burden. As well, the collection methodology was somewhat different in that it was not computer-assisted interviewing that was used, but rather paper questionnaires.
In this first release of NLSCY data, only data from the 10 provinces have been included. Data for the territories have not yet been processed and will be part of a future release sometime during 1997. When the data for the Yukon and NWT are released, an updated version of this guide will be produced with a full discussion of the sample design and content for the Territories Component.
All further discussion in this current version of the microdata guide will be limited to the design and content for the 10 provinces (i.e., the Main the and Integrated Components).
4.2.4 The Child Sample
Once a sample of households was selected for the NLSCY the next step was to select children.
For the Main Component one child 0 to 11 years of age who lived the majority of the time in each selected household was selected at random.
Then other children in the same economic family as this selected child were selected at random up to a maximum of four children per household.
For the Integrated Component a child had already been selected for the health survey as described above. As was done for the Main Component, additional children in the same economic family were selected at random to a maximum of four children aged 0 to 11.
4.3 Sample Allocation
The NLSCY sample for Cycle 1 was constructed taking two important requirements into consideration. A sufficient sample was required in each of the 10 provinces to allow for the production of reliable estimates for all children 0 to 11 years of age. The sample allocation was derived such that the smaller provinces had sufficient sample to meet this requirement.
A second requirement was that it was necessary to have a large enough sample to produce estimates at the Canada level by seven key age groupings or cohorts: 0 to 11 months, 1, 2 to 3, 4 to 5, 6 to 7, 8 to 9, and 10 to 11 years. These groupings will permit analysis every two years by these specific age cohorts while maintaining an overemphasis in the youngest age groups (0 to 11 months and one year olds) which was a requirement for the survey. For the NLSCY Main Component it was possible to oversample households which contained at least one child in the youngest two age groupings to allow for the sample requirements for these age groups.
4.4 Sample Size
The first cycle of the NLSCY resulted in a responding sample of 13,439 households. In these responding households 22,831 children 0 to 11 years of age were selected to participate in the survey. The following tables provide a breakdown of these children by province and by age.
PROVINCE RESPONDING SAMPLE SIZE AGE IN YEARS . . SAMPLE SIZE
Newfoundland . . . . . . . . . . . . 1,232 0 . . . . . . 2,227
Prince Edward Island . . . . . . . . 764 1 . . . . . . 2,469
Nova Scotia . . . . . . . . . . . . 1,532 2 . . . . . . 1,963
New Brunswick . . . . . . . . . . . 1,426 3 . . . . . . 1,946
Quebec . . . . . . . . . . . . . . . 4,065 4 . . . . . . 1,935
Ontario . . . . . . . . . . . . . . 6,020 5 . . . . . . 1,793
Manitoba . . . . . . . . . . . . . . 1,789 6 . . . . . . 1,800
Saskatchewan . . . . . . . . . . . . 1,878 7 . . . . . . 1,750
Alberta . . . . . . . . . . . . . . 2,185 8 . . . . . . 1,780
British Columbia . . . . . . . . . . 1,940 9 . . . . . . 1,734
TOTAL . . . . . . . . . . . . . . . 22,831 10 . . . . . . 1,766
11 . . . . . . 1,668
TOTAL . . . . . . 22,831
5.0 Data Collection
Data collection for Cycle 1 of the NLSCY took place between the fall of 1994 and spring of 1995. There were two major forums under which data were collected; namely the household collection and the school collection.
5.1 The Household Collection
For the household collection, data were collected from a variety of respondents using different data collection methods. Below is a description of each type of questionnaire used in the household.
The Household Roster
The first step was to complete a Household Roster for each household in the NLSCY sample with a knowledgable household member. This roster asked for basic demographic information for each household member as well as some questions on dwelling conditions. As part of the roster, a "relationship grid" was completed. This grid was used to establish the relationship of everyone in the household to everyone else in the household. Using this relationship information it was possible to derive a series of variables to describe the family situation of the child as discussed in Section 8.4.
Once the household roster was completed, the computer system randomly selected one child 0 to 11 years of age living in the household. A question was asked as to which person in the household was the Person Most Knowledgeable about that child. This person was labelled as the PMK for this household. In most cases the PMK was the mother of the child. More information about the PMK is presented in Section 8.3.
The PMK was then asked to complete a set of three questionnaires: the General Questionnaire, the Parent Questionnaire, and the Child Questionnaire. Proxy reporting was permitted as discussed in Section 5.5.
The Parent Questionnaire
The purpose of the Parent Questionnaire was to gather general health information for both the PMK and her spouse/partner and to get some general information on the child's social environment including mental health of the PMK, social support, family functioning and characteristics of the neighbourhood.
The General Questionnaire
The General Questionnaire was completed for both the PMK and the spouse/partner of the PMK. The purpose of the General Questionnaire was to collect socio-economic information for the PMK and spouse/partner. Topic areas included education, labour force and income.
In future cycles of the NLSCY, the Parent and the General Questionnaires will be combined to form one survey instrument, for each of the PMK and spouse/partner.
The Child's Questionnaire
The Child's Questionnaire was completed for selected children in the household, aged newborn to 11 years. Children in the same economic family as the originally selected child (on the household roster) were selected at random to a maximum of four (including the originally selected child). A maximum of four was used for respondent burden reasons. Topic areas on the Child's Questionnaire included among others, health, behaviour, education, literacy, parenting, child care and custody history.
The PPVT-R
The Peabody Picture Vocabulary Test - Revised (PPVT-R) was administered by the interviewer to each selected child aged four to five. Verbal permission was requested of the PMK before the test was administered. The purpose of the test was to measure school readiness of the child. More information about this test is presented in Section 9.21.
Once the entire NLSCY interview had been completed and the Interviewer had left the household she/he completed an assessment questionnaire to assess the conditions under which the test was administered to indicate factors which may have influenced the child's responses and his/her overall reaction to the test.
The 10-11 Questionnaire
This questionnaire was self-completed by each child aged 10 to 11 selected for the NLSCY sample. When the PMK gave permission, the Interviewer provided the questionnaire to the child and encouraged the child to complete the questionnaire in a private setting. Upon completion, the questionnaire was sealed in an envelope to ensure confidentiality of the child. The parent was not permitted to see the child's completed questionnaire. She was informed of this before she gave permission for the child to complete the questionnaire. It was hoped that this procedure would increase the likelihood that the child would provide accurate and honest information.
The objective of this questionnaire was to collect information directly from the child on a variety of aspects of his/her life in order to supplement, and in subsequent analyses, compare with information obtained from the parent and teacher. Some of the topic areas covered were friends and family, school, feelings and behaviours, smoking and drinking and activities.
Neighbourhood Observation by Interviewer
Once the Interviewer left the respondent's home, she/he completed a questionnaire (on the computer) giving her/his perceptions of the neighbourhood in which the respondent resided. This information is intended to supplement the information on the neighbourhood provided by the PMK.
All of the information for the household collection (except for the 10 to 11 Questionnaire) was collected in a face-to-face or telephone interview using computer-assisted interviewing (CAI). Questions were asked to the respondent in the home or by telephone and directly entered into a computer by the interviewer. This made it possible to perform some on the spot edits and basic quality checks to detect errors and to correct errors with the help of the respondent if necessary.
More information about the content of these various questionnaires included in this first release of NLSCY data can be found in Section 9 of this document.
5.2 The School Collection
The school collection was another very important element of the NLSCY. For all children in the Cycle 1 sample who were attending school, the PMK was asked to give written permission to allow for information to be collected from the child's teacher and principal. In cases where the child was in grade 2 or above the PMK was asked to give permission to allow the teacher to administer a short mathematics computation test to the child. Thus, the school collection involved three questionnaires. These questionnaires were mailed out to teachers and principals, who were asked to complete the questionnaires and mail them back to Statistics Canada in the envelopes provided.
The Teacher's Questionnaire
The goal of the Teacher's Questionnaire was to collect information about the child's academic achievement and behaviour at school, as well as information on characteristics of the class and the teacher's instructional practices.
The Principal's Questionnaire
The goal of the Principal's Questionnaire was to gather information on the school environment in order to assess how this may impact child development. Consequently, the Principal's Questionnaire collected information on school policies, resources and educational climate, rather than data about a specific child.
The Math Computation Test
The math test that the teacher was to administer was a shortened version of the Mathematics Computation Test of the standardized Canadian Achievement Tests, Second Edition (CAT/2). CAT/2 is a series of tests designed to measure achievement in basic academic skills.
5.3 Computer-Assisted Interviewing
Data collection for the NLSCY relied heavily on computer-assisted personal interviewing (CAPI) technology. The CAPI system has two main parts; Case Management and the survey specific part.
The Case Management system controls the case assignment and data transmission for the survey. For the NLSCY, a case refers to a household selected for the NLSCY sample. The Case Management system also automatically records management information for each contact (or attempted contact) with respondents, and provides reports for the management of the collection process.
The Case Management system routes the questionnaire applications and sample file from headquarters to the regional offices, and from the regional offices to the interviewer laptops. The returning data take the reverse route. All data is encrypted for transmission, and the data are unencrypted only once resident on a separate secure computer with no external access.
The survey-specific part of CAPI includes an introductory component with procedures for contact and selection of households. Once a contact has been made and household composition has been established, the CAPI system generates applicable questionnaire components dependent on the household composition and the outcome of the selection procedures. For Cycle 1 of the NLSCY, some of the specific components that were generated included a Parent and General Questionnaire for the PMK and spouse/partner and Child's Questionnaire for up to four children aged 0 to 11 in each household. These components are discussed in greater detail in Section 5.1.
The use of CAPI technology allowed for high quality collection of complex population-specific content sections. For example, the system facilitated the collection of the relationships of all household members to each other (i.e., the relationship grid). This wealth of information will enable a detailed analysis of family structures, an important concept for analysis of the child information. This type of collection would be very difficult to implement in a paper and pencil environment.
5.4 Survey Timing
The initial plan was to have four collection periods for the household collection. Data for the Main Component were to be collected in December 1994 and February 1995 and data for the Integrated Component in November 1994 and March 1995, coinciding with NPHS selection periods. The main and integrated samples were split between the two potential collection periods. Each of the four collection periods lasted approximately two weeks.
Once collection actually started it was found that the response rate was not as high as originally hoped. Two back-up procedures were put in place to alleviate this situation. One was to allow for the sample to be carried forward to a future collection period in the case of a non-response. For example if in December a household could not be reached because no one was at home for the entire collection period, then this case was sent out again with the February sample and further attempts were made at that time to contact the household.
At the end of the four collection periods it was decided that the response rate could still be improved if more effort were placed on converting non-respondents. In June 1995 all non-responding cases were sent out again to see if these households could be converted to respondents. Statistics Canada's Regional Offices were asked to assign the "best" interviewers to these cases.
The school collection took place from March to June 1995. First, questionnaire packages were mailed to teachers and principals with instructions on how the various instruments should be completed. Approximately one week after the initial mailing a postcard was sent out to thank all respondents and to remind those who had not yet responded to do so. Roughly two weeks later, a second questionnaire package was sent out to teachers and principals who still had not responded. Finally three weeks later non-responding teachers and principals were contacted by telephone and encouraged to participate. It should be noted the school collection was not attempted for households converted in the June follow-up since by this time it was far too late in the school year to allow for this collection to take place.
5.5 Proxy Reporting
For the Child Questionnaire, the Parent Questionnaire and the General Questionnaire, it was intended that the respondent should be the PMK, and indeed in most cases it was the PMK who completed these instruments.
However, in some circumstances information was accepted from another household member. For example, if the PMK was away from home for the duration of the interview period, then information was accepted from another household member. For the Parent and General Questionnaires, the spouse/partner sometimes wanted to provide his own information. The following is a summary of who provided the information for each of these questionnaires.
PROXY REPORTING FOR THE CHILD, PARENT AND GENERAL QUESTIONNAIRES
OTHER
HOUSEHOLD
PMK SPOUSE MEMBER
RESPONDENT RESPONDENT RESPONDENT
Child Questionnaire 97.7% 2.2% 0.1%
Parent Questionnaire for the PMK 99.1% 0.8% 0.1%
Parent Questionnaire for the spouse/partner 92.5% 7.5% -
General Questionnaire for the PMK 98.1% 1.6% 0.3%
General Questionnaire for the spouse/partner 86.4% 13.5% 0.1%
For all other questionnaires that were part of the NLSCY (i.e., the 10 to 11 Questionnaire, the PPVT-R, and the Teacher and Principal Questionnaires) proxy reporting was not permitted.
5.6 Interview Length
For the household collection, the interview length for responding NLSCY households was approximately two hours.
The total amount of time that it took to complete the major questionnaires that were part of the NLSCY household collection are presented in the table below. The table gives median interview times (i.e., the time at which 50% of the cases took more time and 50% took less). It should be noted that all extreme times (high and low) were removed before these times were derived.
TOTAL INTERVIEW TIMES IN MINUTES
QUESTIONNAIRE . . . . . . . . . . . . INTERVIEW TIME FOR RESPONDING HOUSEHOLDS
All questionnaires in the household interview . . . . . . . . . . . . 119
All Child Questionnaires for the household . . . . . . . . . . . . . 44
All Parent Questionnaires for the household
(for the PMK and spouse/partner) . . . . . . . . . . . . . . . . 11
All General Questionnaires for the household
(for the PMK and spouse/partner) . . . . . . . . . . . . . . . . 14
Total for major components (Child, Parent, General & PPVT) . . . . . 74
Remaining Components . . . . . . . . . . . . . . . . . . . . . . . . 39
The following table gives the median interview times for various family scenarios. The number of selected children (0 to 11) in the household was the factor that had the strongest impact on interview length. For households for which the PMK had a spouse/partner and four children, the interview length was well over three hours, and in some cases took over four hours. For Cycle 2 of the NLSCY a decision has been made to complete child interviews for a maximum of two children per household in order to reduce response burden.
TOTAL INTERVIEW TIMES BY FAMILY TYPE
FAMILY TYPE . . . . . . . . . . . . . TIME IN MINUTES
PMK, spouse and 1 child . . . . . . . . . . . . . 95
PMK, spouse and 2 children . . . . . . . . . . . 134
PMK, spouse, and 3 children . . . . . . . . . . . 169
PMK, spouse, and 4 children . . . . . . . . . . . 200
PMK, no spouse, and 1 child . . . . . . . . . . . 85
PMK, no spouse, and 2 children . . . . . . . . . 127
PMK, no spouse, and 3 children . . . . . . . . . 161
PMK, no spouse, and 4 children . . . . . . . . . 182
5.7 Interview Training, Supervision and Control
The NLSCY was conducted by Labour Force Survey interviewers. All LFS interviewers are under the supervision of a staff of senior interviewers who are responsible for ensuring that interviewers are familiar with the concepts and procedures involved in the survey, and also for periodically monitoring their interviewers and reviewing their completed documents. Senior interviewers ensure that prompt follow-up action is taken for refusal and other non-response cases. If necessary, non-response cases are transferred to the senior and reassigned. The senior interviewers are, in turn, under the supervision of the LFS program managers, located in Statistics Canada regional offices.
For the NLSCY a combination of classroom training and self-study materials were prepared to ensure that interviewers had a proper understanding of survey concepts. The self-study involved the interviewers reading the Interviewer's Manual prepared for the survey and completing home study exercises. During the classroom portion of the training, a program manager or a senior interviewer presented an overview of the survey, went through a mock interview with the participants, gave more specific training on administering the PPVT-R and presented exercises to help interviewers minimize non-response. In total, 14 hours were devoted to these training activities for each interviewer.
8.0 NLSCY Concepts and Definitions
There are many variables and concepts which are critical to the analysis of the NLSCY data. In this section there is a brief discussion regarding the types of analyses that are possible with the NLSCY data. This is followed by a description of key variables which have been derived to explain the living arrangements of the child and the socio-economic conditions under which the child lives.
The content areas for each section of the various questionnaires used for the first cycle of the NLSCY are presented in the next section.
8.1 Cross-sectional and Longitudinal Estimates
The NLSCY design and sample has been constructed so that it will be possible to produce both cross-sectional and longitudinal estimates. For now, with Cycle 1 data, only cross-sectional estimates are possible. Longitudinal information will be available in all subsequent cycles starting from the second cycle.
The allocation of the Cycle 1 sample was such that is will be possible to produce estimates at the national level for the specific age cohorts and at the provincial level for aggregated age groups. This is true for cross-sectional data as well as longitudinal data.
The longitudinal sample will be comprised of all children sampled for Cycle 1 of the survey in responding households. The plan is to follow these children over time every two years. Analyses of these children will permit researchers the opportunity to perform in-depth studies of the long term impact of risk factors (such as divorce or the onset of a health condition) and protective factors (such as positive interactions with parents or academic success at school) on these children as they move into adulthood. If a child moves out of the household where he or she was sampled at Cycle 1, that child will be traced to wherever he or she resides at future cycles of the survey. From a longitudinal perspective, the child, not the household, is the statistical unit of analysis.
It should be noted that some children who were participants in Cycle 1 of the NLSCY may not participate in the second or subsequent cycles due to a variety of reasons. This is usually referred to as attrition. The numbers of these children will be carefully monitored and every effort will be made to keep these numbers at a minimum. The Cycle 1 sample and its allocation was designed with this in mind and as long as future response rates are not lower than expected the sample will still permit longitudinal research by age cohort at the national level.
In the second and subsequent cycles, it is intended that the NLSCY will add children belonging to age groups no longer covered in the longitudinal sample. For example, for Cycle 2 a panel of children 0 and 1 years of age will be added to the Cycle 2 sample. This augmented sample will allow for ongoing cross-sectional analyses to supplement the primary longitudinal research. As such, at each cycle it will be possible to get a snap-shot of Canadian children of all ages. At the present time, it is not planned that this augmented component of the sample will be followed longitudinally.
It should be noted the children who immigrate to Canada at any point of time after the Cycle 1 sample was selected and who are in the age cohorts covered in the Cycle 1 sample, will not be included in either cross-sectional or longitudinal estimates. Estimates of the number of children immigrating to Canada will be monitored and a decision may be made in the future to introduce a new sample into the NLSCY to cover these children.
8.2 NLSCY Units of Analyses
The unit of analysis for the NLSCY is intended to be the child and eventually the young adult. For each cycle of the NLSCY, extensive information will be gathered on the child's family, parent(s), and neighbourhood.
It is true that families or households are relatively straightforward units of analysis with cross-sectional data but the situation becomes quite problematic with longitudinal data. Households change composition frequently, due to divorce of parents, or children leaving the parental nest. Attempts have been made in other studies to define "longitudinal households" but the implementation of this concept has never been straightforward. No single definition has been found to be appropriate for most analytic tasks, and many definitions exclude the portion of the population that has undergone the change. Unfortunately, this is often a significant as well as interesting population to study. It has been suggested that a superior alternative is to use the individual as the unit of analysis and present family and household variables as a characteristic of the individual.
Thus the file which has been constructed for this first release of NLSCY data consists of child records. In order to understand the family situation, estimates such as of the number of children in single parent families, or the number of children living in low income households, can be produced.
8.3 PMK and Spouse
In each NLSCY household, one child 0 to 11 years of age was selected at random and a question was asked about who in the household was the person most knowledgeable about this child. This person was labelled as the PMK. The intention was that the PMK would provide the information for all selected children in the household and then give socio-demographic information about herself and her spouse/partner. In some rare cases it might have been appropriate to label two different people in a household as PMKs. For example, in the case of a step family,it may have been appropriate to label the mother as the PMK for one child and the father for another. However, in order to simplify the interview procedures, only one PMK was selected per household.
The following is the breakdown of the relationship of the PMK to the NLSCY children for Cycle 1.
- for 91.3% of responding children, the PMK was the mother (89.9% the
biological mother and 1.4% the step, adoptive or foster mother) - for 8.2% of the children the PMK was the father
- for 0.5% of children the PMK was not a parent.
When the PMK was not a parent, for the majority of cases the child had a parent living in the household but the parent was not selected as the PMK. For the most part this situation occurred when a child had a very young mother living with her own parents i.e., the child's grandparents, and the grandmother was selected as the PMK. Only 0.1% of the children did not live with a parent.
If the PMK had a partner residing in the household at the time of the interview, then this person was labelled as the spouse. Spouses included both married and common-law partners. Detailed socio-economic information was collected about the spouse/partner in order to describe the family situation of the child.
The following is the breakdown of the relationship of the spouse/partner to the NLSCY children.
- for 14.4% of the children, the PMK did not have a spouse/partner residing in the household
- for 78.1% of children the spouse/partner was the father (73.2% the biological father and 4.9% the step, adoptive or foster father)
- for 7.2% of children the spouse/partner was the mother (biological, step, adoptive or foster)
- for the remaining 0.3% of children, the spouse/partner was not a parent.
8.4 Family Derived Variables
Using NLSCY data, a child's family may be described in several different ways. Many of the family variables that have been used to describe the NLSCY children were derived from what is known as the relationship grid. As part of the household roster some basic demographic information was collected for all members of the child's household. As part of this questionnaire, the relationship of everyone in the household to everyone else was asked. Using this information it was possible to create an extensive set of variables to describe the child's family situation.
The following are some of the family derived variables for the child that exist on this first microdata file for the NLSCY. The names of the derived variable are given in brackets.
Single-parent family
There are two ways of describing the parental situation of children using NLSCY data.
Using the relationship grid, a child's single-parent status was derived. There were 84.2% of children living with two parents, 15.7% with one parent and 0.1% without a parent (ADMCD04).
A child's parent status can also be defined in terms of the PMK. There were 84.3% of the NLSCY children living in a household where the PMK had a spouse/partner; and for 15.7% of children the PMK did not have a spouse/partner (ADMPD06A).
The two ways of describing the child's family are very similar. The only reason for the small differences is a result of the few cases where the child lived with a parent, but the parent was not selected to be the PMK.
Step, Blended and Intact Families
Children living with two parents are classified as being members of intact, step and/or blended families based on the relationship of these children to the parents.
Intact family
An intact family consists of a married or common-law couple where all children are the natural and/or adopted offspring of both members of the couple. For the NLSCY children, 75.5% were a member of an intact family (ADMCD16).
Step family
A step family consists of a married or common-law couple residing in the same household, with at least one step child living with them who is the biological or adopted child of one parent but not the other parent. It should be noted that a child who is the biological child of both parents is said to belong to a step family if at least one of these parents hasa step child residing in the household. For the NLSCY children, 4.6% were step children themselves (ADMCD03) and 8.6% lived in a step family (ADMCD15).
Blended family
Blended families combine children who have different relationships with their parents. A blended family consists of a married or common-law couple living with at least two children, one of whom does not share the same natural and/or adoptive parents as the other child(ren). The following are examples of blended families:
- a couple with biological children of the female partner as well as biological children of the male partner (i.e., hers and his)
- a couple with biological children of the female partner as well as children out of the new union (i.e., hers and theirs).
The blended family is a sub-set of the step family. For the NLSCY children, 6.1% were members of a blended family (ADMCD14).
Economic Family
For the NLSCY, an economic family is defined as all family members related by blood, marriage, common-law relationship or adoption; foster children are considered to be part of the economic family. For example, if a woman lives in a household with her spouse and two children as well as her sister and her sister's child then all of these individuals would be part of one economic family. If a boarder also resided in the household with her child then this would constitute a second economic family.
Siblings
For the NLSCY data, siblings include full, half, step, adopted and foster siblings. Only siblings residing in the household have been included in the calculation of the sibling derived variables included on the microdata file. In the case of common-law relationships, if both members have brought their own children into the relationship then these children are considered as siblings. It should be noted that the classification of siblings was age independent. If an NLSCY child had an adult sibling (for example, 21 years of age) living in the household then this sibling was included in the calculation of the sibling derived variables. The sibling derived variables include total siblings, as well as number of older siblings, younger siblings and siblings of exactly the same date of birth; i.e., twins (ADMCD08, 09, 10 and 11).
8.6 Geographical Indicators
The NLSCY sample was allocated so that provincial analyses will be possible for broad age groupings of children. A variable to indicate province of residence is available on the microdata file (AGEHD03). It was necessary to suppress the province codes on some records on the microdata file due to confidentiality concerns. This is discussed further in Section 9.2.
Sub-provincial analyses may be possible for certain variables, but in order to ensure confidentiality of respondents, sub-provincial indicators have not been included on the microdata file. Census metropolitan area (CMA) is available on the NLSCY master file (AGEHD02) as well as an indicator urban/rural class size (AGEHD01). User's interested in performing sub-provincial analyses or having the province code available for all records can request custom tabulations or make use of the remote data access service as discussed in Section 13.
13.3 Remote Access Requests
During the past few years, as the surveys conducted by Statistics Canada have grown in scope and the number of variables collected increased substantially, suppression and collapsing of confidential variables has
become a source of concern for many users of the data. This is particularly true for users of longitudinal data sets such as the NLSCY. As the number of variables collected about NLSCY survey respondents grows over time, more and more is known about these individuals and the protection of the person's confidentiality becomes a difficult task. At the same time, if the variables collected cannot be made readily available to users, it becomes difficult to justify the expense required to collect these variables. Often these are the very variables that are critical to a complete and comprehensive analyses of the survey data.
Statistics Canada has been striving to find a solution to this problem. In order to somewhat alleviate the problem, for the NLSCY, a procedure has been implemented whereby "place holders" for all confidential variables have been introduced on microdata file and the metadata associated with these variables have been provided (i.e., univariate distributions of the confidential variables at the aggregate level have been included in Section 14). In this way users of NLSCY data can be aware of the confidential variables which are available on the master file and can contact Statistics Canada to request special "custom" tabulations on these variables if so desired. Unfortunately custom tabulations can be a somewhat iterative and potentially costly procedure.
For this first release of NLSCY an alternative approach is being investigated. A service which has been labelled as "Remote Access" is being proposed as a way to reduce direct involvement by Statistics Canada personnel in dealing with custom requests. With Remote Access, researchers gain access to an "enhanced" public use microdata file and directly formulate and test retrieval code, including queries on confidential variables. The code for these custom tabulations are transmitted electronically to Statistics Canada via the INTERNET, and moved into the Department's internal, secure environment. Next, the code would be processed on a PC, the results vetted for confidentiality, and shipped back to the client.
It should be noted that the onus is with the user to submit retrieval programs which are correct and tested. Statistics Canada will review results only for confidentiality concerns and will not make any assessment whatsoever as to whether or not the submitted program has worked properly. Initially, there should be some discussion to ensure that Statistics Canada has a copy of the software used in the submitted program.
This service will be offered to researchers who have purchased a NLSCY microdata file. The microdata file for the NLSCY has been structured as described above so there are "place holders" for all confidential variables and the metadata for these variables is available (in Section 14). The Remote Access Service is still at the pilot stage, so initially the service will be offered free of change (until the end of 1997). At that time the project will be evaluated and an appropriate costing algorithm will be developed. The goal will be to keep the cost at a minimum since the burden of the work will rely with the user and not Statistics Canada personnel. Users interested in making use of this service can get in touch with Statistics Canada contacts mentioned in Section 1.