The correct answer is meta-analysis. Meta-analysis is statistical analysis that combines results from multiple researches to increase power over individual studies and improve estimates of the size of certain effect. Advantages of this method are: results can be generalized to a larger population, the precision and accuracy of estimates can be improved as more data is used, inconsistency of results across studies can be quantified and analyzed, moderators can be included to explain variation between studies, hypothesis testing can be applied on summary estimates and the presence of publication bias can be investigated