Levels of Evidence - Pyramid
Click on each level in the pyramid to learn more about each level of evidence.
Level I:
Experimental study, randomized controlled trial (RCT)
Sources:
- Systematic review of RCTs, with or without meta-analysis
- Critically Appraised Topic (Evidence synthesis)
- Critically Appraised Individual Topics (Article Synopsis)
Level II:
Quasi-experimental Study
Systematic review of a combination of RCTs and quasi-experimental, or quasi-experimental studies only, with or without meta-analysis
Sources:
- Systematic review of RCTs, with or without meta-analysis
- Critically Appraised Topic (Evidence synthesis)
- Critically Appraised Individual Topics (Article Synopsis)
Level III:
Non-experimental study
Systematic review of a combination of RCTs, quasi-experimental and non-experimental, or non-experimental studies only, with or without meta-analysis
Qualitative study or systematic review, with or without meta-analysis
Sources:
- Systematic review of RCTs, with or without meta-analysis
- Critically Appraised Topic (Evidence synthesis)
- Critically Appraised Individual Topics (Article Synopsis)
Level IV:
Opinion of respected authorities and/or nationally recognized expert committees/consensus panels based on scientific evidence
Sources:
Clinical practice guidelines
Consensus panels
Level V:
Based on experiential and non-research evidence
Sources:
- Literature reviews
- Quality improvement, program or financial evaluation
- Case reports
- Opinion of nationally recognized expert(s) based on experiential evidence
