Ned Tijdschr Geneeskd. 2006 Nov 11;150(45):2484.
Nederlands tijdschrift voor geneeskunde
[Article in Dutch] J J E van Everdingen
PMID: 17137094
A classification of scientific evidence into 'levels', in which the type of research design is graded according to its strength, is useful because it helps the medical community to sort out a system that is accepted all over the world. It not only makes the highest levels of evidential value explicit for a particular clinical question, but also makes the lack of evidence visible. Selected articles will contain labels identifying the strength of evidence supporting key recommendations.