Hello Deepak,

Do you mean:

1. how to determine the number of effect size estimates to enter in a meta-analytic study;

2. how to determine what sample size was used in a specific study that you'd like to include in your meta-analysis, but the sample size wasn't reported by author(s);

3. something else?

For #1, one generally seeks a census sample (all relevant ES estimates). Once you start imposing restrictions on what studies may be used (e.g., use of a specific measure, specific population, or specific treatment/intervention), the usual problem is that there are only a few studies that meet all criteria, rather than too many.

For #2, the most direct method would be to contact the authors. If that doesn't work, then, if some statistical data are given, it is possible many times to infer the sample size.

For #3, you'll need to elaborate more in your query.

Good luck with your work.

https://www.slideshare.net/drsrb/sample-size-amp-meta-analysis

Deepak k s

One approach may be to calculate the sample size from the total participants of each study included in your meta--analysis.

Hello Deepak,

I don't know if you mean the sample size of each study, or the total set of the sample that you are going to analyze in the meta-analysis.