DR-301d · Module 2

Reliability vs. Credibility

3 min read

Credibility is a point-in-time assessment: how trustworthy does this source appear right now? Reliability is a longitudinal assessment: how often has this source been correct over time? A new source can have high credibility — the right credentials, the right domain, the right specificity — and unknown reliability because there is no track record. An established source can have moderate credibility on any given finding but high reliability because it has been consistently accurate over fifty previous uses. Reliability is earned. Credibility is assessed. Both are necessary.

Do This

  • Track source accuracy over time — did the claims check out when verified downstream?
  • Maintain a reliability score separate from the credibility score — they measure different things
  • Let reliability override credibility when they conflict — a source that is consistently right deserves more weight than a source that looks authoritative but has been wrong before

Avoid This

  • Conflate credibility with reliability — a credible-looking source with no track record is unknown, not trusted
  • Assume reliability is permanent — a source that was reliable for three years can degrade without warning
  • Ignore reliability data when it contradicts your intuition about a source's credibility