The last three decades the accumulation of quantitative research evidence has led to the development of systematic methods for combining information across samples of related studies. Although a few methods have been described for accumulating research evidence over time, meta-analysis is widely...

Field experiments that involve nested structures may assign treatment conditions either to entire groups (such as classrooms or schools), or individuals within groups (such as students). Since field experiments involve clustering, key aspects of their design include knowledge of the intraclass...

Evidence from Project STAR has suggested that on average small classes increase student achievement. However, thus far researchers have focused on computing mean differences in student achievement between smaller and larger classes. In this study I focus on the distribution of the small class...

Previous findings from experimental and non-experimental studies have demonstrated that teachers differ in their effectiveness. In addition, evidence from non-experimental studies has indicated that teacher effects can last up to five years. This study used high-quality data from a four-year...

Given that previous findings on the social distribution of the effects of small classes have been mixed and inconclusive, in the present study I attempted to shed light on the mechanism through which small classes affect the achievement of low- and high-achieving students. I used data from a...

Meta-analytic methods have been widely applied to education, medicine, and the social sciences. Much of meta-analytic data are hierarchically structured since effect size estimates are nested within studies, and in turn studies can be nested within level-3 units such as laboratories or...

In experimental designs with nested structures entire groups (such as schools) are often assigned to treatment conditions. Key aspects of the design in these cluster randomized experiments include knowledge of the intraclass correlation structure and the sample sizes necessary to achieve...

The impact of schools on student achievement has been of great interest for the last four decades. This study examines trends of school effects on student achievement employing three national probability samples of high school seniors: NLS:72, HSB:82, and NELS:92. Hierarchical linear models are...

Multilevel models are widely used in education and social science research. However, the effects of omitting levels of the hierarchy on the variance decomposition and the clustering effects have not been well documented. This paper discusses how omitting one level in three-level models affects...

The impact of schools on student achievement has been of great interest for the last four decades. This study examines trends of school effects on student achievement employing three national probability samples of high school seniors: NLS:72, HSB:82, and NELS:92. Hierarchical linear models are...