Advanced Meta-Analysis in Psychology
Synthesizing Psychological Evidence
Random-Effects Modeling
Meta-analysis quantitatively synthesizes effect sizes across studies. Because psychological studies rarely share exactly the same true effect (due to different populations or methods), a Random-Effects model is preferred. The weight of each study incorporates both within-study variance and between-study variance :
Heterogeneity Metrics
Correcting for Publication Bias
Publication bias can severely distort meta-analytic estimates. Always use visual tools and statistical methods like trim-and-fill, p-curve analysis, or PET-PEESE to assess and correct for small-study effects and publication bias.
In a meta-analysis, what does the statistic represent?
is an intuitive metric representing the proportion of observed dispersion that is real. An of 75% indicates high heterogeneity.
Correct answer: The percentage of total variation across studies due to heterogeneity rather than chance.
What visual tool is commonly used in meta-analyses to detect publication bias by plotting effect sizes against their standard errors?
A funnel plot displays study precision against effect size. Asymmetry in the plot (especially missing small studies with negative results) is indicative of publication bias.
Correct answer: Funnel plot
PRISMA Guidelines for Systematic Reviews
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1
Identification: Search databases with predefined boolean strings.
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2
Screening: Review titles and abstracts against inclusion/exclusion criteria.
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3
Eligibility: Full-text review of remaining articles.
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4
Included: Final selection of studies for quantitative synthesis.