How Not To Sort By Average Ratin

how Not to Sort by average rating

rating的错误方式

• Score = (Positive ratings) − (Negative ratings)

  • item 1: 1000 ratings (600 positive ratings, 400 negative ratings)
  • item 2: 10000 ratings(5500 positive ratings, 4500 negative ratings)
    item1不应该放在item2前面

• Score = Average rating = (Positive ratings) / (Total ratings)

  • item 1: 1 positive , 0 negative
  • item 2: 100 positive , 1 negative
    item 1 不应该放在item2前面

rating的正确公式

Score = Lower bound of Wilson score confidence interval for a Bernoulli parameter
评分给定下，95%的可能性positive rating的真实比例至少是多少

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(pos：积极评分的数目 n: 总评分的数 confidence:置信率)
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应用场景(不限于sorting)

• 检测垃圾邮件: What percentage of people who see this item will mark it as spam?
• 创造best of list: What percentage of people who see this item will mark it as “best of”?
• most emailed list: What percentage of people who see this page will click “Email”?

How Hacker News ranking algorithm works

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随着时间的增长，得分变低。同时gravity增加的时候得分会减少地更快

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对于old stories，时间影响变小（曲线平滑，主要依赖于vote）
对于new stories，是时间和vote的同时作用

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How Reddit ranking algorithms work