Fixed-effect vs. random-effect meta-analysis

[Mahdie Raj]

Hello,
I wonder to know what meta-analysis model must be used to compute a combined effect across subgroups within a study: fixed effect or random-effects? and why?
Thanks

[Carlo Lazzaro]

Mahdie:
with such scant details about your actual problem, I can only point you to the valuable textbook by Alex Sutton and Collegues https://www.wiley.com/en-us/Methods+...-9780471490661