{"type":"post","id":"updating-the-eci-methodology-to-use-a-bayesian-6c0092","slug":"updating-the-eci-methodology-to-use-a-bayesian-6c0092","title":"Updating the ECI methodology to use a Bayesian model","description":"Epoch AI says it has replaced the frequentist model behind its Epoch Capabilities Index (ECI) with a Bayesian model.","retrieval_nugget":"Epoch AI says it has replaced the frequentist model behind its Epoch Capabilities Index (ECI) with a Bayesian model. The change produces probability-based uncertainty estimates and direct comparisons between models, while leaving frontier scores largely similar and lowering scores for many weaker models. Readers of model rankings should therefore distinguish methodology changes from capability changes.","published_at":"2026-11-11","updated_at":"2026-11-11","record_date":"2026-11-11","date_kind":"published_at","topics":["claude"],"entities":["Epoch AI","Epoch Capabilities Index","Emilia Álvarez","Alexander Barry","Claude 3.5 Sonnet","GPT-5"],"related_patterns":[],"novelty_label":"new_fact","what_changed":"Epoch has replaced the ECI’s frequentist scoring methodology with a Bayesian model, improving uncertainty estimates while leaving frontier scores largely unchanged.","prior_refs":["https://newruntime.com/posts/gemini-is-the-closest-it-s-been-to-43ce2b/","https://newruntime.com/posts/claude-fable-5-2-scored-174-on-the-2701ba/"],"source_url":"https://epoch.ai/publications/eci-bayesian-methodology","source_urls":["https://epoch.ai/publications/eci-bayesian-methodology"],"schema_version":"newruntime-agent-readable-v0.2","stable_id":"post:updating-the-eci-methodology-to-use-a-bayesian-6c0092","status":"published","visuals":[],"editor":{"role":"editor","name":"Andrey Reshetnikov","profile":"https://newruntime.com/owner-profile.md","profile_json":"https://newruntime.com/owner-profile.json","same_as":["https://www.linkedin.com/in/reshetnikov1/","https://t.me/lapetuse"]},"routes":{"html":"https://newruntime.com/posts/updating-the-eci-methodology-to-use-a-bayesian-6c0092/","markdown":"https://newruntime.com/posts/updating-the-eci-methodology-to-use-a-bayesian-6c0092.md","json":"https://newruntime.com/posts/updating-the-eci-methodology-to-use-a-bayesian-6c0092.json"},"markdown_url":"https://newruntime.com/posts/updating-the-eci-methodology-to-use-a-bayesian-6c0092.md","next_reads":[{"type":"topic","path":"/topics/claude/","url":"https://newruntime.com/topics/claude/","title":"Claude","reason":"Explore the claude topic hub.","media_type":"text/html","markdown_url":"https://newruntime.com/topics/claude.md","json_url":"https://newruntime.com/topics/claude.json"},{"type":"collection","path":"/posts/","url":"https://newruntime.com/posts/","title":"Field Notes","reason":"Open the latest editorial analysis.","media_type":"text/html","json_url":"https://newruntime.com/posts.json"},{"type":"collection","path":"/sources/","url":"https://newruntime.com/sources/","title":"Sources","reason":"See the original sources this archive cites.","media_type":"text/html"}]}