How the SCI score works

The Skill Credibility Index (SCI) is a number from 0 to 100 that represents how credible a person's claimed skill is — based entirely on verifiable evidence, not self-assertion.

The five components

SCI is built from five independent components, each with its own evidence sources and cap. No single component can dominate the score.

• Practice (cap: 25). Hours spent in peer learning sessions, weighted by role (teaching contributes more than learning).
• Proof (cap: 40). Assessment results, completed projects, and peer-verified demonstrations. The highest-weight component because it requires active evidence production.
• Reliability (cap: 20). Session completion rate, no-show rate, and consistency of engagement. A practitioner who teaches consistently is more credible than one who taught once.
• Freshness (cap: 15). How recent the evidence is. A skill last evidenced three years ago decays slowly toward zero. Active practitioners never worry about this.
• Integrity (modifier). A multiplier applied based on peer validation quality. Endorsements from higher-tier practitioners in the same skill amplify the score.

Trust tiers

The SCI score maps to a trust tier displayed on your passport. Tiers are not just labels — they determine what endorsements you can give, what sessions you can lead, and how your passport appears to employers using the Verify API.

The tiers run from Beginner (0–30) through Practitioner (31–55), Verified (56–75), and Expert (76–90), to Master (91–100). Each tier requires evidence across multiple components — you cannot reach Verified through Practice alone.

Why the formula is public

Every point in your SCI score is traceable to a specific event: a session on a specific date, an assessment with a specific result, a peer endorsement from a named practitioner. The formula itself is published in Lemma's methodology docs.

This is intentional. Trust requires transparency. A credential system that won't show its work is asking you to trust the institution. Lemma is asking you to trust the math — and the math is auditable.