The basic formula for Hacker News ranking has been known for years, but questions remained about invisible factors and penalties. Analysis of the top 60 stories revealed that 20% of front-page stories get penalized in various ways. The published formula is mostly accurate but includes significant tweaking.

Anything with "NSA" in the title is penalized and drops off quickly, though updates note HN no longer applies this specific penalty. A "controversial" story gets severely penalized after hitting 40 comments. Articles are scored based on upvote score, time since submission, and various penalties.

Because time has a larger exponent than votes, an article's score eventually drops to zero. For efficiency, stories are reranked only occasionally; when upvoted, they move to appropriate spots. To prevent stories from getting stuck in high positions without new votes, the top 50 stories are randomly selected and reranked every 30 seconds.

Pages can also be cached for 90 seconds. Raw scores and the #1 spot vary throughout the day. Articles shoot up rapidly then slowly drop.

The observed peak is faster due to high initial voting rates that drop off. Some articles score well but get stuck behind more popular ones. Penalties can cause rapid drops; for example, "Getting website registration completely wrong" was penalized for controversy and dropped, allowing other stories to reach #1. "Apple Maps" also lost its top spot after a controversy penalty.

The Snapchat article was penalized so heavily it dropped off the chart. "Why you should never use Mongo DB" was hugely popular but languished around #7 due to heavy penalties. The controversy penalty applies rapidly to stories reaching high positions.