Meta-analyses have become the gold standard for synthesizing evidence from multiple clinical trials, and they are especially useful when outcomes are rare or adverse since individual trials often lack sufficient power to detect a treatment effect. However, when zero events are observed in one or both treatment arms in a trial, commonly used…

Partial correlation coefficients are often used as effect sizes in the meta-analysis and systematic review of multiple regression analysis research results. There are two well-known formulas for the variance and thereby for the standard error (SE) of partial correlation coefficients (PCC). One is considered the "correct" variance in the…

It has been debated whether teachers should treat students' grammatical errors in second language writing instruction (Truscott, 1996, 1999, 2010; Ferris, 1999, 2004, 2010). Several meta-analyses have investigated correction effects (e.g. Russell & Spada, 2006; Truscott, 2007). Their findings, however, have been conflicting. A recent trend to…