Most empirical tests of mediation utilize cross-sectional data despite the fact that mediation consists of causal processes that unfold over time. The authors considered the possibility that longitudinal mediation might occur under either of two different models of change: (a) an autoregressive model or (b) a random effects model. For both models,…

Supplemental Instruction (SI) incorporates collaborative learning in small, peer-led, group settings in order to integrate instruction in learning and reasoning skills with course content. Several meta-analyses speak to the efficacy of SI but fail to address selection bias due to ability/motivation and gender. In this study, SI was paired with a…

The major youth psychotherapy meta-analyses have relied on published studies, which may have led to biased effect size estimates. To examine this possibility, the authors compared 121 dissertations with 134 published studies and found the following: (a) few differences on individual methodological variables, but, overall, stronger methodology in…

A meta-analysis was performed on the 133 cognitive and behavioral papers in autism using comparison groups in the 1999-2002 period. High-functioning (average IQ: 84.7), adolescents (average, 14.4 years) are largely dominant. IQ is the most frequent matching variable in use (51.2%). The instruments that are most frequently used to determine IQ or…