Data Collection Procedure

The ECLS-B collected information from children, parents, child care and early education providers, and teachers. The ECLS B dataset also includes information about the schools the study children attended in kindergarten.


In every round of data collection, trained assessors visited children in their homes. With the parent's permission, children participated in activities designed to measure important developmental skills in the cognitive, socioemotional,1 and physical domains.

9-month round. During the first data collection, when study children were approximately 9 months of age, children’s cognitive and motor skills were assessed using a modified version of the Bayley Scales of Infant Development (BSID-II), called the Bayley Short Form—Research Edition (BSF-R). Children’s socioemotional development was assessed through a taped interaction with their primary caregiver (i.e., the parent respondent) using the Nursing Child Assessment Teaching Scale (NCATS). All children had their length (i.e., height), weight, and middle-upper arm circumference (MUAC) measured. Additionally, children born with very low birth weight had their head circumference measured.

2-year round. During the 2-year collection, the BSF-R again was used to measure cognitive and motor development. A different taped interaction, the Two Bags Task, was used to assess children’s socioemotional development. A modified Q-sort was included in the 2-year collection to assess the quality of children's attachment to their primary caregiver. Again, all children had their height, weight, and middle-upper arm circumference (MUAC) measured, and children born with very low birth weight had their head circumference measured.

Preschool round. For the preschool collection, the ECLS-B child assessment protocol was modified to take into account the study children’s growing competencies and to focus more on indicators of school readiness. The BSF-R was replaced with an early reading and mathematics assessment similar to the assessments used in the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 (ECLS-K) kindergarten and first grade collections. Unique to the preschool wave was the assessment of children’s knowledge of basic colors. Fine motor skills were assessed by asking children to copy a series of forms/shapes drawn by assessors and to build structures using blocks. Gross motor skills were assessed by asking children to jump, balance on one foot, hop on one foot, skip, walk backward along a line, and catch a bean bag. Additionally, as in the previous waves, children’s social interactions with the parent respondent were assessed using the Two Bags Task. All children had their height, weight, and middle-upper arm circumference (MUAC) measured, and children born with very low birth weight had their head circumference measured.

Kindergarten 2006 & kindergarten 2007 rounds. The kindergarten cognitive assessments were similar to the preschool assessments; one exception was that the assessment of color knowledge was not included. The early reading and mathematics assessment at kindergarten built on the preschool assessment by assessing more difficult knowledge and skills. Fine and gross motor skills were directly assessed again, but socioemotional development was assessed indirectly through questions asked of both parents and teachers. As in the previous waves, all children had their height, weight, and middle-upper arm circumference (MUAC) measured, and children born with very low birth weight had their head circumference measured.


Trained assessors also conducted a computer-assisted interview with the sampled child's primary caregiver, most frequently the mother, in every round of data collection. Parents were asked to provide information about the sampled child, themselves, the home environment, parenting attitudes, and family characteristics. Questions regarding family structure, child participation in nonparental care and education arrangements, household income, and community and social support also were included. In the kindergarten rounds, questions about the children’s school experiences were asked. Fathers (both resident fathers and nonresident biological fathers) completed self-administered questionnaires in the 9-month and 2-year data collections that covered topics such as the role they play in parenting and their attitudes toward fatherhood. Resident fathers also completed self-administered questionnaires in the preschool wave.

Early Care and Education Providers

With the permission of the child's parents, individuals and organizations that provided regular nonparental care and education for the child were interviewed. Trained staff conducted a computer-assisted interview over the phone. For home-based care settings, the primary provider was interviewed about the setting and the sampled child's experiences there. For center-based settings, first the center director was asked for general information about the program, and then the sampled child's primary provider in the center was interviewed about the group environment and the child's experiences. Both home- and center-based primary providers were asked about their own background and experiences. A subsample of the settings were directly observed and rated using standardized instruments for assessing quality (the Family Day Care Rating Scale (FDCRS) for home-based settings at 2 years and preschool, the Infant-Toddler Environment Rating Scale (ITERS) for center-based settings at 2 years, and the Early Childhood Environment Rating Scale (ECERS) for center-based settings at preschool). Additionally, information on child-to-caregiver ratios was obtained through repeated counts of children and providers, and the provider’s interactions with the children were assessed using the Arnett Caregiver Interaction Scale (1989).

Teachers and Schools

Kindergarten teachers of ECLS-B children completed questionnaires that captured information about the teacher, the sampled children, their classrooms, and their schools. School data were obtained from teachers and from NCES’s universe data files (the Common Core of Data (CCD) and Private School Survey (PSS)).

Inclusion and Assessibility

The ECLS-B worked to include all sampled children and families. Within the limits of time and fiscal constraints, materials were developed to include children and families whose primary language was not English. For example, both the parent interview and the early care and education provider interview were translated into Spanish. If the parent or provider felt more comfortable speaking in a language other than English or Spanish, then translators were utilized when available.

Additionally, at 9 months and 2 years, the child assessments were administered in the child's primary language either by a bilingual interviewer or with the assistance of a translator. At preschool and kindergarten, children’s English language skills were assessed at the beginning of the cognitive assessments. Children who did not demonstrate sufficient English language skills to complete the assessment in English were either routed to a comparable assessment in Spanish (if Spanish-speaking) or else excluded from the cognitive assessments. Regardless of English language skills, all study children were administered the motor items (via a translator if needed) and their physical measurements were taken. The level of English language proficiency that children needed to demonstrate to be included in the assessments administered in English was set very low; as a result, relatively few children were excluded from the cognitive assessments administered in English. Also, all children’s English language skills were reassessed at kindergarten regardless of their demonstrated proficiency at preschool. Consequently, children who were excluded at preschool were administered the cognitive assessments in English at kindergarten if they demonstrated sufficient English language skills when they were reassessed at the beginning of the kindergarten assessment. Children with disabilities were included in the sample. The ECLS-B was designed to maximize participation of children with special needs at every data collection wave. Accommodations were allowed when necessary. Exclusion from the assessments was considered on a case-by-case basis; in most cases where an exclusion occurred, a child was excluded only from certain components of the assessment (e.g., children in wheelchairs did not have their gross motor skills assessed) rather than from the entire assessment. Children requiring Braille or sign language were excluded from the cognitive assessments and were given a modified motor assessment.

1 Socioemotional development was not directly assessed in the kindergarten rounds.