Meta-analysis is a statistical process for combining the results of many studies to draw more accurate conclusions about a phenomenon. The most basic goal of meta-analysis is to gain higher confidence in a result by using larger sample sizes to show that a result is statistically consistent.
Meta-analysis techniques also allow specific measurement of the consistency and robustness of results, particularly across changes or improvements in experimental design.
Parapsychologists have made extensive use of meta-analysis in recent decades to add more formal rigor and statistical strength to psi research, as well as to experimentally test criticisms of psi research. With the use of meta-analysis techniques, evidence in support of psi has gone from good to astronomical, and scientific criticisms of psi research can be explicitly evaluated (See "The Conscious Universe").