Appendix A: The National Longitudinal Survey of Children and Youth

The National Longitudinal Survey of Children and Youth (NLSCY) is a long-term study of Canadian children that follows their development from birth to early adulthood. The NLSCY began in 1994, and is conducted by Statistics Canada. The survey is sponsored by Human Resources and Social Development Canada. The survey is designed to collect information about factors influencing the social, emotional and behavioural development of children, and to monitor the impact of these factors on their development over time. The survey covers a broad range of topics including health, physical development, learning, behaviour, and social environment (family, friends, schools and communities).

Survey design. The NLSCY sample frame in the first cycle of the survey, in 1994/1995, was based on the Labour Force Survey (LFS), a monthly survey of households in Canada conducted by Statistics Canada. Households with children aged 0 to 11 years were selected from the LFS in 1994 to participate in the NLSCY. Of 26,000 eligible households, 23,000 responded.

The first cycle of the NLSCY was conducted in 1994 and early 1995. The longitudinal cohort from that cycle has been monitored every two years since then, with data collection taking place in 1994/1995, 1996/1997, 1998/1999, 2000/2001, 2002/2003. New panels of children have been added to the survey each year. For information about changes to the sample frame over that time, the reader is referred to the Microdata User Guide for cycle 5 (Statistics Canada, n.d.b).

The present sample. The sample of children studied here includes 5-year-old children in the third longitudinal cohort of the NLSCY. These children were born between April and December in 1997. They were 5 years old as of December 31, 2002, during the cycle 5 collection phase. At the time of interview, they ranged from 57 to 65 months old, with a small number being slightly older. Of the 4,916 children born in 1997 who were recruited in cycle 3, 3,923 responded in cycle 5, for a retention rate of 79.8%. These 3,923 children were included in the present analysis. Applying the cross-sectional survey design weights indicates that these children represented around 360,000 5-year-old children in the Canadian population. Note that because of the sample selection procedure, no children who were born in the first four months of the year are included in the study; therefore, and conclusions apply to a population of 5-year-olds that is relatively young.

Partial non-response.  Response rates for variables that were provided by the reporting parent were all over 95%. These variables included all child and family characteristics, all readiness to learn measures that were not direct measures, and all home environment variables. Because non-response was so low for these variables, its effect on findings would be small, and it was ignored in the analyses.

Direct measures used in this report included the Peabody Picture Vocabulary Test – Revised (PPVT-R; receptive vocabulary score), the Number Knowledge Assessment (number knowledge score), and  Who Am I? (copying and symbol use score). Response rates for the direct measures were lower than for parent-reported measures, for various reasons. Response rates were:

Receptive vocabulary score: 90.6%
Number knowledge score: 90.7%
Copying and symbol use score: 86.9% 

A discussion of reasons for partial non-response and a detailed analysis of non-response for each of these measures is reported in the Microdata User Guide for cycle 5 (Statistics Canada, n.d.b, p. 110-114). The analysis found that response rates for the receptive vocabulary test depended on English or French language ability, province of residence, and education level of the reporting parent. Response rates for the number knowledge assessment and for the copying and symbol use test depended on province of residence. These trends must be taken into account when interpreting the findings in the present report.