random effect vs. fixed effect in STATA by using STATA commands

when random effect model is appropriate. Using stata commands

[@animeshchowdhury448]

Sir,
I am currently working on a meta analysis. But I am not able to produce association studies of allele contrast (A vs a). Except that all are done but can not understand how to calculate A vs a frequency. If you help me out it will help me a lot.
Thanks

[@madeeasy7691]

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