Key points are not available for this paper at this time.
We are currently wimessing an "epidemic" of meta-analyses and overviews in the scientific literature. This is a relatively new phenomenon and this article addresses some of the important issues raised by their increasing use. In particular the differing applications and limitations of meta- analysis are discussed, with a review of the analytic methods used and the problems and biases encountered.
Spector et al. (1991) studied this question.