title: On the meta-analysis of response ratios for studies with correlated and multi-group designs.
abstract: A common effect size metric used to quantify the outcome of experiments for ecological meta-analysis is the response ratio (RR): the log proportional change in the means of a treatment and control group. Estimates of the variance of RR are also important for meta-analysis because they serve as weights when effect sizes are averaged and compared. The variance of an effect size is typically a function of sampling error; however, it can also be influenced by study design. Here, I derive new variances and covariances for RR for several often-encountered experimental designs: when the treatment and control means are correlated; when multiple treatments have a common control; when means are based on repeated measures; and when the study has a correlated factorial design, or is multivariate. These developments are useful for improving the quality of data extracted from studies for meta-analysis and help address some of the common challenges meta-analysts face when quantifying a diversity of experimental designs with the response ratio.
authors.affiliation: Department of Integrative Biology, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA. lajeunesse@usf.edu
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Lajeunessei
mesh_terms: D003627:Data Interpretation, Statistical; D004463:Ecology / Q000379:methods*; D017753:Ecosystem; D015201:Meta-Analysis as Topic; D012107:Research Design