Evidence Quality
Every relationship and prediction in Galen carries quality metadata. Understanding these signals helps you calibrate how much to trust each piece of information.
Confidence scores
Relationships include a confidence field (0.0 to 1.0) reflecting the strength and consistency of the evidence. Higher confidence means more independent sources agree on the relationship.
0.0 — 0.3
Weak / single source
0.3 — 0.7
Moderate / multiple sources
0.7 — 1.0
Strong / cross-validated
Grounded sources
The grounded_sources field lists which databases contributed evidence for a relationship. More sources means higher reproducibility. Cross-database validation (e.g., a drug target confirmed by both ChEMBL bioactivity and DepMap CRISPR knockouts) is the gold standard.
PCH layer distribution
When querying entity profiles or subgraphs, the response includes a PCH layer breakdown showing what fraction of relationships are L1 (association), L2 (intervention), or L3 (counterfactual). A higher L2+L3 fraction means more experimentally validated causal evidence.
Next: Data Sources
The 28 databases that feed the knowledge graph — what each contributes and how they're integrated.
Read about data sources →