Meta Analysis: definition, meaning and steps to conduct

Meta Analysis - Toolshero

Meta-analysis: This article explains the concept of meta-analysis in a practical way. The article begins with an introduction to this concept, followed by a definition and a general explanation. You will also find a practical example and tips for conducting a simple analysis yourself. Enjoy reading!

What is a meta-analysis?

Have you ever wondered how doctors and researchers often make the right decisions about complex (medical) treatments? A powerful tool they use is the so-called meta-analysis. With this approach, they combine the results of multiple scientific studies to get a clearer picture of the overall effectiveness of a treatment.

Definition and meaning

But what exactly is meta-analysis? It’s a research process that systematically brings together the findings of individual studies and uses statistical methods to calculate an overall or ‘absolute’ effect.

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It’s not just about merging data from smaller studies to increase sample size. Analysts also use systematic methods to account for differences in research approaches, treatment outcomes, and sample sizes.

For example, they also test the sensitivity and validity of their results for their own research protocols and statistical analyses.

Admittedly, that sounds difficult. It can also be described as putting puzzle pieces together to see the bigger picture. According to experts, scientists are often confronted with valuable but sometimes contradictory results in individual studies.

Meta-analyses play an important role in putting these puzzle pieces together and combining the findings of multiple studies to provide a more complete understanding.

Due to the combination of several scientific studies, it is considered the most comprehensive form of scientific research. This creates more confidence in the conclusions drawn, as a larger body of research is considered.

A practical example

Imagine this: there are several studies examining the same medical treatment, and each study reports slightly different results due to some degree of error.

Meta-analysis helps the researcher by combining these results to get closer to the truth.

By using statistical approaches, an estimated mean can be derived that reflects the common effect observed in the studies.

Steps in conducting a meta-analysis

Meta-analyses are usually preceded by a systematic review, as this helps identify and assess all relevant facts. It is an extremely precise and complex process, which is almost exclusively performed in a scientific research setting.

The general steps are as follows:

  1. Formulating the research question, for example by using the PICO model
  2. Searching for literature
  3. Selection of studies based on certain criteria
  4. Selection of specific studies on a well-defined topic
  5. Deciding whether to include unpublished studies to avoid publication bias
  6. Determining which dependent variables or summary measures are allowed
  7. Selection of the right model, for example a fixed-effect or random-effect meta-analysis
  8. Investigating sources of heterogeneity between studies, for example by meta-regression or by subgroup analysis
  9. Following formal guidelines for conducting and reporting the analysis as described in the Cochrane Handbook
  10. Use of Reporting Guidelines

By following these steps, meta-analyses can be performed to obtain reliable summaries and conclusions from a wide range of research data.


Meta-analyses have very valuable advantages.

First, it provides an estimate of the unknown effect size, which helps us understand how effective a treatment really is.

It also allows us to compare and contrast results from different studies. It helps identify patterns between the findings, uncover sources of disagreement, and uncover interesting connections that may emerge when multiple studies are analyzed together.


However, like any research method, meta-analysis also has its limitations. A concern is possible bias in individual studies due to questionable research practices or publication bias.

If such biases are present, the overall treatment effect calculated via this type of analysis may not reflect the true efficacy of a treatment.

Another challenge lies in dealing with heterogeneous studies.

Each study can have its own unique characteristics and produce different results. When we average these differences in a meta-analysis, the result may not accurately represent a specific group studied.

It’s like averaging the weight of apples and oranges – the result may not accurately represent both the apples and the oranges.

This means that researchers must make careful choices during the analysis process, such as how to search for studies, which studies to select based on specific criteria, how to handle incomplete data, analyze the data, and take publication bias into account.

Despite these challenges, meta-analysis remains a valuable tool in evidence-based research.

It is often an essential part of systematic reviews, where multiple studies are extensively analyzed. By combining evidence from different sources, it provides a more comprehensive insight into the effectiveness of medical treatments, for example.

Meta-analysis in psychology

Meta-analysis plays an important role in various fields, including psychology. It provides value primarily through its ability to bring together results from different studies.

Imagine there are many little puzzle pieces of information scattered across different studies. Meta-analysis helps us put all those pieces together and get a complete picture.

It helps psychologists discover patterns and trends and draw more reliable conclusions about certain topics, such as the effectiveness of a treatment or the relationship between certain factors.

Using this type of analysis, psychologists can better understand what really works and how different studies together have greater value.

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Now it’s your turn

What do you think? Do you recognize the explanation of meta-analysis? Have you ever heard of this research method? Have you ever performed this analysis yourself? What do you think are the benefits its use? How would you explain its importance to someone who has no experience with research methods? What tips or comments can you share with us?

Share your experience and knowledge in the comments box below.

More information

  1. Guzzo, R. A., Jackson, S. E., & Katzell, R. A. (1987). Meta-analysis. Research in organizational behavior, 9(1), 407-442.
  2. Becker, B. J. (2000). Multivariate meta-analysis. Handbook of applied multivariate statistics and mathematical modeling, 499-525.
  3. Haidich, A. B. (2010). Meta-analysis in medical research. Hippokratia, 14(Suppl 1), 29.
  4. Field, A. P., & Gillett, R. (2010). How to do a meta‐analysis. British Journal of Mathematical and Statistical Psychology, 63(3), 665-694.

How to cite this article:
Janse, B. (2024). Meta Analysis. Retrieved [insert date] from Toolshero:

Original publication date: 06/27/2024 | Last update: 06/27/2024

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Ben Janse
Article by:

Ben Janse

Ben Janse is a young professional working at ToolsHero as Content Manager. He is also an International Business student at Rotterdam Business School where he focusses on analyzing and developing management models. Thanks to his theoretical and practical knowledge, he knows how to distinguish main- and side issues and to make the essence of each article clearly visible.


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