What type of meta-analysis are we talking about? What data will you include?

I think we need a concrete example.

Actually, I wanted to find out the significance difference in the carbon estimation  using two different allometric equations.  So, I became interested to know a little bit broader view on data types and proper effect size calculation.

Sorry, you lost me on the first line there! But if you want to know whether different data types (e.g. continuous or categorical) lead to different ways of estimating associations or effects, then yes they do. But it's such a broad topic, I wouldn't know where to start. Good luck.

Thank you Darren.