Oxford CEBM Evidence-Level Classifier
Pick the design of a study or claim you’re evaluating; the tool returns the Oxford CEBM level of evidence it corresponds to, along with cautions specific to that tier.
What the Oxford CEBM framework is
The Oxford Centre for Evidence-Based Medicine Levels of Evidence framework is a widely-used hierarchy for grading clinical evidence. Level 1a (systematic review of homogeneous RCTs) sits at the top; Level 5 (mechanism argument, expert opinion, in-vitro / animal-only) at the bottom. Full framework at cebm.ox.ac.uk.
How this maps to our A–X evidence grades
Oxford CEBM levels and our A–X evidence grading system measure related but distinct things — CEBM grades study design; A–X grades the total body of evidence for a claim (which pools multiple designs). Roughly, Level 1a-b corresponds to Grade A; Level 2 to Grade B; Level 3 to Grade C; Level 4-5 to Grades D–X.
What this tool is not
- Not a substitute for reading the actual paper.
- Not a comment on external validity — a well-designed Level 1b RCT in a narrow trial population still doesn’t generalise to arbitrary readers.
- Not a replacement for clinical judgement — CEBM levels are inputs to decision-making, not conclusions.