The Early Childhood Longitudinal Study (ECLS) program includes three longitudinal studies that examine child development, school readiness, and early school experiences. The birth cohort of the ECLS-B is a sample of children born in 2001 and followed from birth through kindergarten entry.ﾠThe ECLS program provides national data on children's status at birth and at various points thereafter; children's transitions to nonparental care, early education programs, and school; and children's experiences and growth through the eighth grade. The ECLS program also provides data to analyze the relationships among a wide range of family, school, community, and individual variables with children's development, early learning, and performance in school.
The Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) selected a nationally representative probability sample of children born in 2001. Births were sampled within a set of primary sampling units (PSUs) and in some cases secondary sampling units (SSUs) in order to control data collection costs. Children were mostly sampled via registered births from the National Center for Health Statistics (NCHS) vital statistics system (Hetzel 1997). This clustered list-frame design allowed for maximum, efficient coverage of the target population and was considered preferable to other approaches that would involve large screening efforts or coverage errors (e.g., sampling hospitals and other birthing places, augmenting household surveys, or sampling birth certificates available at a variety of levels: NCHS, state registrars, and county and local records offices). Over 14,000 births were sampled and fielded and yielded 10,688 9-month cases with at least a completed interview with the child's parent.