# Statistics help with a meta-analysis?

I do not have any experience doing statistics with data from a meta-analysis. However, I am working on a research project at the moment where I must look for a significant difference between groups in the meta-analysis. But my project advisor is off at the moment and I would like to begin this part of the project before he returns. So, I was wondering if someone with experience doing meta-analyses can help me?

There are 3 groups in this meta-analysis (group A,B and C). Each group has a different population and different number of people in each group. Each study in the meta-analysis gives me a proportion of individuals with Thyroid cancer for each group (A,B and C). I would like to find if there is a significant difference in prevalence of Thyroid cancer between the 3 groups. I am a bit confused about how to do this? Do I use a T-test to find the sig. difference in each individual study? Do I find the weighted average of the proportions in each group (ie averaging out the proportions for each study in each of the 3 groups) and then do the t-test? Would it be best to use another statistical test?

@mdewey I have about 50 studies in the meta-analysis. Not all of them use the exact same 3 groups. Some only use one of the groups and others use all 3 (none of them use 2 groups). I have the proportions for each study and group in the study. For example, if a study has 3 groups, then I will have a proportion for each of the groups. I would like to find out if there's an overall significant difference in proportions between the 3 groups.

• Do you mean you have a number of primary studies each of which used exactly the same three groups? Do you have just the proportions or do you have numerator and denominator? – mdewey Feb 25 '17 at 16:47
• @mdeweyI have about 50 studies in the meta-analysis. Not all of them use the exact same 3 groups. Some only use one of the groups and others use all 3 (none of them use 2 groups). I have the proportions for each study and group in the study. For example, if a study has 3 groups, then I will have a proportion for each of the groups. I would like to find out if there's an overall significant difference in proportions between the 3 groups. – aspire94 Feb 25 '17 at 17:16
• In a meta-analysis, you pick one hypothesis - that's comparing two groups. Then you find the estimate of the difference between the groups (possibly standardized) and its standard error. You don't do a t-test. – Jeremy Miles Feb 25 '17 at 19:01
• @JeremyMiles But how does that tell you if there is a significant difference? – aspire94 Feb 25 '17 at 20:45
• Your comment which someone has kindly edited into the question for you does not answer all my question. Do you have the absolute frequencies or just proportions? – mdewey Feb 26 '17 at 12:40

Having said all that you are studying thyroid cancer and although this has a good prognosis none the less human lives may be at stake here and I think you should consider getting expert help locally as if you thought that a $t$-test might work here you may need some more help than we can give you on a question and answer site.