What are meta-analytic studies? When would you want to use a meta-analytic study?

Question

What will be an ideal response?

Answer 1

Meta-analytic studies use statistical procedures that find the average effect size, an indicator of the strength of the relationship between the independent variables on the dependent variables. Effect sizes in meta-analytic studies are often reported as correlation coefficients though other statistics may be used instead. For r, a small effect size is in the range of .10, a medium effect size is around .30, and a large effect size is .50 or greater. Effect sizes may also be reported as standard deviation units. As a general reference, consider that one-half a standard deviation unit is considered a medium effect size and one standard deviation unit is generally regarded as a high medium-to-large effect size.

Although there are some poor meta-analytic studies because of lax inclusion standards, in general, the investigators who conduct meta-analyses usually attempt to screen out poor methodological studies and include only the higher quality ones. Thus, we get relatively stable indicators of the effects of particular causal variables. When studying the relationship between stress and illness, as well as stress and health in general, the meta-analytic strategy gives us a great advantage in furthering our understanding. Therefore, special attention is given throughout this book to meta-analytic studies.