In meta-analysis, what do fixed-effect and random-effects models assume, and when would you prefer a random-effects model?

In meta-analysis, what do fixed-effect and random-effects models assume, and when would you prefer a random-effects model?

• A. Fixed-effect assumes a common true effect; random-effects assume a distribution of true effects across studies
• B. Fixed-effect assumes a distribution of true effects; random-effects assumes a single true effect
• C. Fixed-effect assumes a common true effect; random-effects assumes variability in true effects across studies
• D. Fixed-effect accounts for study quality; random-effects ignores heterogeneity

Answer: (C)