How Hacker News ranking works: scoring, controversy, and penalties (2013)
2 hours ago
- Articles are ranked based on upvotes, submission time, and penalties using a formula with gravity exponent.
- Efficiency is achieved by reranking articles only when upvoted or randomly every 30 seconds, with 90-second page caching.
- Automatic penalties apply to titles with 'NSA' and certain domains (e.g., arstechnica.com, github.com), with factors from 0.25 to 0.8.
- Controversy penalties heavily penalize articles with more comments than upvotes and at least 40 comments, often causing sudden ranking drops.
- Approximately 20% of front-page articles and 38% of second-page articles are penalized, based on empirical analysis of raw scores and observed anomalies.