Registered Nurses' Association of Ontario

Levels of Evidence

LEVEL SOURCE OF EVIDENCE
Ia Evidence obtained from meta-analysis or systematic reviews of randomized controlled trials and/or synthesis of multiple studies primarily of quantitative research.
Ib Evidence obtained from at least one randomized controlled trial.
IIa Evidence obtained from at least one well-designed controlled study without randomization.
IIb Evidence obtained from at least one other type of well-designed quasi-experimental study, without randomization.
III Evidence obtained from the synthesis of multiple studies primarily of qualitative research.
IV Evidence obtained from well-designed non-experimental observational studies, such as analytical studies or descriptive studies, and/or qualitative studies.
V Evidence obtained from expert opinion or committee reports, and/or clinical experiences of respected authorities.

 

Addiction and Mental Health
Integrating Smoking Cessation into Daily Nursing Practice
Practice Recommendations