Source: Current opinion in obstetrics & gynecology [1040-872X] Farquhar, Cynthia yr:2006 vol:18 iss:4 pg:433 -9 Explains in depth the methods of a systematic review, including meta-analysis. Also lists common errors.
What are Systematic Reviews?
Systematic Reviews are, at their simplest level, comprehensive evidence reviews on a specific topic (e.g., programs, interventions, research questions). Exhaustive literature searches are completed and located evidence (i.e., journal articles) is analysed, synthesized, compared, assessed for quality, and summarized. Systematic reviews began in the clinical sciences and typically use randomized controlled trials (RCT) as the 'gold standard' in terms of evidence.
Since the use of RCTs can often be unethical in population or public health studies, systematic reviews are less common in the population or public health literature. However, in recent years more studies that use qualitative methodology have begun to be included in systematic reviews. An important background article on systematic reviews is:
Mullen PD, Ramirez G. The promise and pitfalls of systematic reviews. Annual Review of Public Health. 27:81-102, 2006. [PubMed]
The systematicreview "movement" that has transformed medical journal reports of clinical trials and reviews of clinical trials has taken hold in public health, with the most recent milestone, the publication of the first edition of The Guide to Community Health Services in 2005. In this paper we define and distinguish current terms, point out important resources for systematicreviews, describe the impact of systematicreview on the quality of primary studies and summaries of the evidence, and provide perspectives on the promise of systematicreviews for shaping the agenda for public health research. Several pitfalls are discussed, including a false sense of rigor implied by the terms "systematicreview" and "meta-analysis" and substantial variation in the validity of claims that a particular intervention is "evidence based," and the difficulty of translating conclusions from systematicreviews into public health advocacy and practice.