Assessing publication bias in coordinate-based meta-analysis techniques?

Specific coordinate-based meta-analysis methods have been developed to integrate the results of fMRI studies. Results that do not reach statistical significance are less likely to be published and included in a meta-analysis. Meta-analyses of fMRI studies are prone to this publication bias when studies are excluded because they fail to show activation in specific regions. In this study we propose an adaptation of the Fail-Safe N (FSN; Rosenthal, 1979) . The FSN reflects the number of null studies, i.e. studies without activation in a target region, that can be added to an existing meta-analysis without altering the result for the target region. We simulated 1000 meta-analyses and calculated the FSN for an original meta-analysis of 3 contributing studies in a target region. We varied the thresholding method of the meta-analysis and the sample size of the individual studies. We found that the FSN increases if the thresholding method is less stringent and decreases with an increasing sample size.

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