Decomposing variables into between and within components are often required in multilevel analysis. This method of decomposition should not ignore possible unreliability of an observed group mean (i.e., arithmetic mean) that is due to small cluster sizes and can lead to substantially biased estimates. Adjustment procedures that allow unbiased…

Two previous studies examining 5 empirical educational psychology research journals (Hsieh et al., 2005; Robinson, Levin, Thomas, Pituch, & Vaughn, 2007) found that in the 21-year period from 1983 to 2004, there was a decrease in intervention and randomized experimental research, whereas in the 10-year period from 1994 to 2004, there was an…

This meta-analysis used hierarchical linear modeling to examine 115 single-case studies with 343 participants that examined the effectiveness of social skills interventions for individuals with autism spectrum disorder (ASD). The average effect size of the included studies was 1.40 (SD = 0.43, 95% CL = 1.32-1.48, N = 115). In the further, several…

The goal of the present study is to demonstrate the ways in which multilevel models can be applied to family research. We emphasize the conceptual issues in family research that this data analytic technique helps us to address. The family represents a nested, hierarchical structure in which multiple children from the same family are not…