Calculating the confidence interval

I've collected data such as mean  and standard deviation $b$ values for several experimental studies, each of which was examined $n$ cases. I would like to report the results with the confidence level $99\%$, but I'm not sure about the exact formula. Could someone post it?

Some points of Confidence interval question were not clear to me.

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Are you talking about a confidence interval for a mean? Is it the same mean for each of the several experimental studies? –  Michael Hardy Jul 27 '12 at 0:30
Yes. The mean is different, and I would need to account for each study separately. –  user506901 Jul 27 '12 at 8:02