Meta-analysis is a statistical method used to provide a systematic, unbiased way to synthesize the results from multiple studies on the same topic. It has become an important tool in policy research, because it has offered researchers solutions to many of the problems they face. Today, studies on important issues are conducted by different people, using different types of data. Making sense of the different findings can seem impossible. Traditionally, the solution has been to rely on methods such as a literature review, in which researchers provide a brief summary of previous studies and their findings. This method however, is subjective, and scientifically unhelpful, since there is no systematic method by which these literature reviews can combine the findings of various studies. Literature reviews also cannot provide significance tests for the joint outcomes of multiple studies. However, meta-analysis is able to provide both synthesized findings in the form of a combined effect size, and combined significance levels. This means that meta-analysis provides the most reliable estimates of the effects of policy actions.
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