Labels
Every label on Evidence Signal, in plain language.
Evidence levels
Evidence levels describe how much a source lets you trust a claim about learners, based on study design, who took part and what was measured. They are not endorsements, and they are not official WWC, ESSA or GRADE ratings.
Randomized trial not yet human-verified, or a comparison-group study with baseline data, with real learners. Preprints stop here.
Associations in real-learner data with statistical controls, or a comparison without baseline equivalence. Perception- or engagement-only outcomes stop here.
Qualitative, case study, survey, pilot or deployment with real learners or educators, and no comparison group.
Only AI models, simulated students, benchmarks or audits of AI outputs. Tells us about the technology, not about student learning.
Conceptual, opinion, policy or framework work, and news coverage of others' work until the study it describes is itself graded.
A launch, announcement or claim with no traceable study.
No abstract or methods available yet, for example a publisher listing.
Level 4 (strong design, human-verified) exists in our method but is only awarded after a person reads the full paper. No item currently holds it.
Badges
- Preprint: Not yet peer reviewed. Caps the level at 3.
- Peer-reviewed (journal reference listed): The arXiv record lists a journal reference or DOI for a published version.
- Small or imprecise: Fewer than 100 learners and no confidence interval or power analysis.
- Short exposure: A single session or less than a week of use.
- Researcher-made measure: The outcome test was built by the study team with no reliability evidence.
- Vendor-linked: An author, funder or publisher has a stake in the product.
- Perception only: Measures how people feel about a tool, not whether they learned more.
- Open data or materials: Data or materials are publicly available.
- Report (grey literature): A report that did not go through journal peer review.
- Provisional (rules only): Graded by our fixed rules only; the two-grader review has not run yet.
- Simulated learners: Uses AI agents or synthetic students instead of real learners.
- Preregistered: The plan was registered before data were collected.
- Effect size reported: Reports a standardized effect, ideally with a confidence interval.
- Level-4 candidate: Could qualify for the top level, held at Level 3 until a person reads the full paper.
Who took part and what was measured
Reviewed study cards show who took part (K-12 students, higher-ed students, adult learners, teachers, adults acting only as raters, simulated or AI-only, or not reported) and the outcome measured (learning or achievement, behavior, behavior or engagement, perception or attitude, teacher practice, model performance, or not reported). Each card also shows its review status: Confirmed against the published method (AI-assisted review), or human-verified.