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5029238 
Book/Book Chapter 
Chapter 6: Effect sizes : conventional choices and calculations 
Rosenburg, MS; Rothstein, HR; Gurevitch, J 
2013 
Princeton University Press 
Princeton, NJ 
Handbook of Meta-analysis in Ecology and Evolution 
English 
is part of a larger document 5029185 Handbook of Meta-analysis in Ecology and Evolution
One of the fundamental concepts in meta-analysis is that of the effect size. An effect size is a statistical parameter that can be used to compare, on the same scale, the results of different studies in which a common effect of interest has been measured. This chapter describes the conventional effect sizes most commonly encountered in ecology and evolutionary biology, and the types of data associated with them. While choice of a specific measure of effect size may influence the interpretation of results, it does not influence the actual inference methods of meta-analysis. One critical point to remember is that one cannot combine different measures of effect size in a single meta-analysis: once you have chosen how you are going to estimate effect size, you need to use it for all of the studies to be analyzed.