What is evidence?
A common understanding is that “evidence concerns facts (actual or asserted) intended for use in support of a conclusion”. A fact, in turn, is something known through experience or observation. An important implication of this understanding is that evidence can be used to support a conclusion, but it is not the same as a conclusion. Evidence alone does not make decisions. This understanding of what evidence is has a number of implications.
- Firstly, expert opinion is more than just evidence. It is the combination of facts, the interpretation of those facts, and conclusions. Evidence always informs expert opinions. And appropriate use of that evidence requires the identification of those facts (experience or observations) that form the basis of the opinions, as well as an appraisal of the extent to which the facts support the conclusions
- Secondly, not all evidence is equally convincing. How convincing evidence is depends on what sorts of observations were made and how well they were made. Research evidence is generally more convincing than haphazard observations because it uses systematic methods to collect and analyse observations.
- Thirdly, judgements about how much confidence can be placed in different types of evidence (in other words, the ‘quality’ of the evidence) are made either implicitly or explicitly. It is better to make these judgements systematically and explicitly in order to prevent errors, resolve disagreements, facilitate critical appraisal, and communicate information.
More information about finding evidence
Finding systematic reviews
Finding and using research evidence about local conditions
Finding and using research evidence about resource use and costs
Dealing with insufficient research evidence
The EVIPNet Virtual Health Library
The aim of the EVIPNet Virtual Health Library (E-VHL) is to provide quick and easy access to evidence-informed decisions about health issues and specifically health systems in LMICs. The E-VHL aims to be a “clearinghouse”, a one-stop shop and will be give to access information about EVIPNet teams and activities, as well as databases of systematic reviews, policy briefs, and others relevant sources of knowledge and valuable documents.