Research Methods Explained: What Is a Meta-Analysis?

As a health news writer for Health Digest, I am typically assigned to summarize recent research findings that get published in research journals. It might be how long COVID ages the brain, how short bursts of movement throughout the day can benefit your health, or how spironolactone might reduce alcohol cravings. Many of these articles are correlational studies that can’t really determine causation. 

Before we jump on board a particular research result, it’s important for us to remember that a single research study doesn’t mean we should change our behavior. That’s where meta-analysis comes in.

A meta-analysis is a research method that combines the results of multiple studies to produce a more accurate understanding of the topic under investigation.

It is different from a standard research study in that it does not involve any new data collection. Rather, it uses data that has already been collected by other researchers. This can be helpful because it allows us to see patterns and relationships that might not be visible when looking at individual studies.

Meta-analysis is used when the findings of individual studies are inconclusive or when there is heterogeneity (variability) in the results of different studies. By combining the results of several studies, a meta-analysis can produce a more reliable result than any individual study. It is a subset of systematic reviews, which are reviews of the scientific literature that use explicit methods to identify, select, and appraise studies.

Meta-analysis is a powerful tool because it allows us to see the big picture and to understand how different pieces of research fit together. It can help us to answer questions such as: "What are the overall effects of this treatment?" and "What are the most important factors affecting this outcome?"

Use Meta-Analysis to “Do Your Research”

A meta-analysis is a synthesis of the results of multiple studies on a given topic.

By pooling the data from these studies, a meta-analysis can provide a more precise estimate of the effect of a particular intervention or treatment. It can also help to identify any heterogeneity among the studies, i.e. differences in the results that may be due to factors such as study design or the population studied.

This information can then be used to develop new hypotheses about the effects of the intervention or treatment in question. A meta-analysis also reduces the amount of work needed to research a topic, as it brings together all the relevant data in one place.

A meta-analysis also will critique some of the studies. Although there are a ton of peer-reviewed research studies, many studies have significant flaws in their design and protocols. If a meta-analysis isn’t available on your topic, it’s best to analyze a research article to determine its quality.

Types of Studies Used in a Meta-Analysis

A meta-analysis is a quantitative study design that combines the results of multiple research studies.

Typically, these studies are randomized, controlled clinical trials, which provide the most rigorous evidence for a given question. Meta-analyses collect and analyze data from multiple studies to estimate the size of an effect and its variability across studies.

In meta-analysis, researchers combine information from individual studies to identify patterns that might not be apparent when single studies are evaluated independently. By doing this, researchers can determine if an effect holds across different contexts and populations.

Examples of Meta-Analyses

To give you a better understanding of how a meta-analysis works, here are some examples of meta-analyses that have been done. You might hear how yoga might relieve anxiety. In the peer-reviewed journal Depression and Anxiety, researchers conducted a meta-analysis on the effect of yoga on anxiety disorders or elevated levels of anxiety. Yoga has a short-term effect on providing relief from elevated levels of anxiety, but no effect was found for people who were clinically diagnosed with anxiety. The researchers concluded that yoga can help with anxiety relief, but more research might be necessary to help people who are clinically diagnosed with anxiety.

Another meta-analysis you might be interested in is the relationship between running and longevity. In the British Journal of Sports Medicine, researchers found that running can reduce the risk of all-cause mortality (i.e. dying from any reason), cardiovascular death, and cancer death compared to people who don’t run. By pooling the results from 14 studies, the researchers could combine the research sample to more than 200,000 participants. 

Conclusion

A meta-analysis is a study that combines the results of several other studies, in order to get a clearer picture of what the overall effect of a particular treatment or intervention is. It’s a powerful tool, because it can give you an idea of how strong the evidence is for a particular finding.