Meta-analysis is the use of statistical methods to summarize research findi
ngs across studies. Special statistical methods are usually needed for meta
-analysis, both because effect-size indexes are typically highly heterosced
astic and because it is desirable to be able to distinguish between-study v
ariance from within-study sampling-error variance. We outline a number of c
onsiderations related to choosing methods for the meta-analysis of ecologic
al data, including the choice of parametric vs. resampling methods, reasons
for conducting weighted analyses where possible, and comparisons fixed vs.
mixed models in categorical and regression-type analyses.