Programs that improve teaching effectiveness represent a core strategy to improve student educational outcomes and close student achievement gaps. This article compiles empirical values of intraclass correlations for designing effective and efficient experimental studies evaluating the effects of these programs. The Early Childhood Longitudinal…

Researchers have become increasingly interested in programs' main and interaction effects of two variables (A and B, e.g., two treatment variables or one treatment variable and one moderator) on outcomes. A challenge for estimating main and interaction effects is to eliminate selection bias across A-by-B groups. I introduce Rubin's causal model to…

The Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011), is collecting information about the early educational experiences of a nationally representative sample of children who were in kindergarten or who were of kindergarten age in ungraded classrooms or schools in the 2010-11 school year. The data collection began in…

Since its inception, the National Center for Education Statistics (NCES) has been committed to the practice of documenting its statistical methods for its customers and of seeking to avoid misinterpretation of its published data. The reason for this policy is to assure customers that proper statistical standards and techniques have been observed,…

The Early Childhood Longitudinal Study, Birth Cohort 2000 (ECLS-B) is a study that will assess children's health status and their growth and development in domains that are critical for later school readiness and academic achievement. This paper is one of several that have been prepared in support of ECLS-B design efforts. It is anticipated that…

The Early Childhood Longitudinal Study (ECLS) is a new study that will focus on children's early school experiences beginning in kindergarten. Approximately 23,000 children will be selected as they enter kindergarten and followed through fifth grade. Base-year data will be collected in the fall of 1998, but there will a field test in the 1996-97…

The Early Childhood Longitudinal Study (ECLS) is a study that focuses on children's early school experiences beginning with kindergarten. The ECLS was developed by the National Center for Education Statistics. Approximately 23,000 children were selected as they entered kindergarten, and were followed as they moved through fifth grade. This paper…

Recent investigations of the extent to which students with disabilities are allowed to participate in major national data collections used in measurement-driven education reform suggest that 40 to 50 percent of students with disabilities are typically excluded from major assessments, although they are included to a greater degree in assessments…