What do we mean by evidence synthesis?
"...a way of combining information from multiple studies that have investigated the same thing, to come to an overall understanding of what they found"
(From the Cochrane website)
The most well-established evidence synthesis methods are meta-analyses and systematic reviews
Why evidence synthesis?
What is a systematic review?
“…a scientific investigation that focuses on a specific question and uses explicit, pre-specified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies.”
(Source: “Finding What Works in Health Care”, Institute of Medicine)
Types of systematic review questions
Systematic review vs. traditional lit review
|Review Stage||Traditional Review||Systematic Review|
|Review question||Question is broad and terms are not well-defined||Question is specific; terms and protocol are defined in advance|
|Study selection||Convenience sampling and biased selection||Exhaustive searches with pre-defined criteria applied for selection by more than one reviewer|
|Quality assessment||None||Selected studies assessed for risk of bias and study quality|
|Synthesis||Qualitative and narrative; vote-counting may be used||Sometimes quantitative, including meta-analysis with risk of bias considered|
Systematic reviews, scoping reviews, systematic maps and rapid reviews
Key features and best practices in evidence synthesis
The librarian’s role