Dear R-experts! Running a meta-analysis (using the magnificent metafor-package), I use cohen's d as a main outcome measure in a random-effects model. For most of the samples cohen's d is derived form a comparison of two groups (A & B). However some studies report results from an ANOVA (one-factor with three levels: C,D,E) whereas two groups (C,D) correspond to one group in the other studies (B=C,D). Is there a way? The handbook of research synthesis and meta-analysis By Harris M. Cooper says that: d=sqrt((F*(n1+n2)/n1*n2)) for ANOVA (one-factor with two-levels) but does this also hold for ANOVA (one-factor with three levels)?
Many thanks for your help! Jokel [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.