quantitative overview
meta analysis
A method that uses statistical techniques to combine results from different studies and obtain a quantitative estimate of the overall effect of a particular intervention or variable on a defined outcome—i.e., it is a statistical process for pooling data from many clinical trials to glean a clear answer. Meta-analysis produces a stronger conclusion than can be provided by any individual study.Cons
Bias, potential for analytical sloppiness, lack of understanding of basic issues, failure to consider major covariates, and overstating the strengths and precision of the results.