In medical research, an<unk>  is a<unk>  of systematic<unk> s or meta-analyses. They may also be called overviews of<unk> s,<unk> s of<unk> s, summaries of systematic<unk> s, or syntheses of<unk> s.<unk> s are among the highest levels of evidence currently available in medicine. By summarizing information from multiple overview articles,<unk> s make it easier to<unk>  the evidence and allow for comparison of results between each of the individual<unk> s.<unk> s may address a broader question than a typical<unk> , such as discussing multiple different treatment comparisons instead of only one. They are especially useful for developing guidelines and clinical practice, and when comparing competing interventions.
Umbrella review
Semen analysis
Triage
Chronotherapy 
Risk panel
TCN Protocol
Partner notification
Frozen section procedure