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What is a meta-analysis?

A meta-analysis is a type of research study that combines the results of numerous scientific studies that are answering the same question. This approach is useful for improving the strength and statistical power of the overall observed effects from the studies.

Why is a meta-analysis useful?

Meta-analyses are considered to be very useful for decreasing biases, increasing statistical power, and increasing applicability of results. These studies decrease biases by using an objective way of combining data from numerous studies. Smaller studies may collect little data or have a low amount of participants. Meta-analyses increase statistical power by combining the data of multiple studies, therefore expanding the pool of data. By combining data, applicability of results may increase with a larger population and with studies with varying limitations.

How is a meta-analysis conducted?

Meta-analyses are conducted using five main steps. First, a problem or research question must be identified. Using multiple research databases, a literature review is then conducted pertaining to the research question. Next, specific criteria for inclusion and exclusion should be identified regarding which studies will be included in the meta-analysis. The data from the included studies will then be extracted for the meta-analysis. Finally, using specific software, a meta-analysis is then conducted to objectively analyze the data.

What are the disadvantages of meta-analyses?

Although meta-analyses are considered one of the best levels of research evidence, there are disadvantages to this method. These studies require experts for conducting literature reviews and analyzing statistical data. They also require the various research studies being used to be well-conducted, meaning finding the right studies can be time consuming and challenging.

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Photo of Kristin Ricklefs-Johnson

Medically reviewed by:

Kristin Ricklefs-Johnson, Ph.D., RD

Kristin is an RDN who also earned her Ph.D. in Nutrition from Arizona State University with an emphasis on insulin resistance, lipid metabolism disorders, and obesity. She completed her post-doctoral fellowship at Mayo Clinic where she focused on nutrition-related proteomic and metabolic research. Her interests include understanding the exact mechanism of action of various genetic variations underlying individual predispositions to nutrition-related health outcomes. Her goal is to help all individuals prevent chronic diseases and achieve long, healthy lives through eating well.

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