Meta Analysis

The Meta-Analysis Meaning

What do we mean by a meta-analysis?

A meta-analysis is a research technique researchers frequently use in psychology to summarise key findings of multiple studies. The research method collects quantitative, meaning numerical data.

Meta-Analysis in Research

Researchers use a meta-analysis to understand psychology research’s general direction in a specific area.

The research method is also commonly used to identify whether current research supports and establishes existing interventions as effective or ineffective. Or to find a more precise, generalisable conclusion. As meta-analyses utilise multiple studies to form a conclusion, the findings are more likely to be statistically significant as a larger data pool is used.

Meta-Analysis Methodology

When deciding to perform a meta-analysis of existing research, a researcher will typically involve in the following steps:

• Researchers identify the area of interest for the research and formulate a hypothesis.
• Researchers create inclusion/exclusion criteria. For example, in a meta-analysis looking into the effects of exercise on mood, exclusion criteria may include studies using participants that are using medication that affects affective states.

• Researchers will use a database to identify all of the research similar to what the hypothesis is investigating. Several established databases in psychology include published work. In this stage, researchers need to search key terms that summarise what the meta-analysis is investigating to identify studies that also investigated similar factors/ hypotheses.
• Researchers will determine which studies will be used based on the inclusion/exclusion criteria. From the studies found in the database, the researcher must decide whether they will be used.
  • Studies included meeting the criteria of the inclusion criterion.
  • Studies excluded meeting the criteria of the exclusion criterion.
• Researchers appraise the research studies. Appraising studies is a crucial stage in the meta-analysis methodology that checks the reliability and validity of included studies. Studies low in reliability or validity are usually not included in the meta-analysis.

• Once they have compiled the information and statistically analysed the results, they can form a conclusion of whether the analysis supports/disproves the hypothesis initially proposed.

Meta-Analysis Example

Van Ijzendoorn and Kroonenberg (1988) performed a meta-analysis to identify cross-cultural and intra-cultural differences between attachment styles.

The meta-analysis reviewed a total of 32 studies from eight different countries. The inclusion criteria of the meta-analysis were studies that used:

1. The strange situation was used to identify attachment styles.

2. The studies investigated mother-infant attachment styles.

3. The studies used the same attachment classification system as in Ainsworth’s Strange Situation – type A (insecure avoidant), type B (secure), and type C (insecure avoidant).

Studies not meeting these requirements were excluded from the analysis. Further exclusion criteria included: studies that recruited participants with developmental disorders.

The results of the meta-analysis were the following:

• Secure attachments were the most common attachment style in each country analysed.

• Western countries had a higher mean score of insecure-avoidant attachments than Eastern countries.

• Eastern countries had a higher mean score of insecure-ambivalent attachments than Western countries.

This meta-analysis example showed the importance of meta-analysis in research as it allowed the researchers to compare the data from multiple countries relatively quickly and cheaply. And it would have been too difficult for the researchers to independently collect primary data from each of the eight countries due to time, cost and language barriers.

Meta-Analysis vs Systematic Review

Meta-analysis and systematic review are standard research techniques used in psychology. Although similar research processes, stark differences between the two exist.

A systematic review is one of the stages of the meta-analysis methodology. During a systematic review, the researcher uses a precise method to collect relevant studies from scientific databases relevant to the research area. Like a meta-analysis, the researcher creates and uses inclusion/ exclusion criteria. Rather than giving a quantitative summative figure, it identifies and summarises all the relevant research concerning the research question.

Advantages and Disadvantages of Meta-Analysis

Let’s discuss the advantages and disadvantages of meta-analysis in psychology research.