系统与基础设施danluu.com
可疑的不连续性
Suspicious Discontinuities
2020 — 2024，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
Dan Luu 的这篇文章分析了各种数据中出现的“可疑的不连续点”：当某个指标跨越特定门槛时，人们的行为会发生突变，导致数据分布出现异常的尖峰或断崖。文章列举了收入报告、评分系统等多个例子，说明人们会围绕这些门槛“钻空子”。
为什么经久不衰：它揭示了一个普遍且反直觉的现象——任何硬性门槛都会扭曲人们的行为和数据，这一洞察在政策设计、数据分析中至今适用。
HN 评论精选
以侄女放弃加薪工作的真实案例说明福利悬崖的扭曲激励，并指出政策修补往往制造更多悬崖
这些不连续点带来的扭曲激励是救助类项目最糟糕的缺陷之一。举个真实例子：我侄女离异带着三个孩子，抚养费时有时无，于是领了食品券，同时想找更好的工作。她面试成功，但对方给的薪水比她能继续领食品券的上限刚好高出每小时 0.5 美元，又低于她现在的工作，加上工会规定不能降低标准工资，结果她只好放弃这份工作。国会注意到这类扭曲激励后，常见的做法是推出条款更复杂的新项目，但更多的档位和规则往往制造出更多的悬崖（尽管每个悬崖上的激励扭曲会小一些）。另一种思路是惩罚“滥用系统”的人，比如限制领福利的年限——可当年那些长期领福利的单亲妈妈，部分正是因为在家带孩子比去做低薪工作还要付托育费更划算。
btilly查看英文原文
The perverse incentives around these discontinuities is one of the worst misfeatures of programs intended to help people. Here is a real example. My niece wound up with 3 kids, divorced, with inconsistent child support payments. So she went on food stamps. She was looking for a better job. She found one, interviewed, and they wanted to hire her. But the salary that they offered was $0.50/hour too much for her to stay on food stamps, and was less than her current job. Thanks to union regulations, the person who wanted to hire her couldn't pay her less than the standard salary. The result is that she did not take the job. A common result when Congress takes note of perverse incentives like this is that they introduce a more complex program with specific terms that address specific problems that emerged. The problem is that by creating more brackets and more complex rules you usually create MORE cliffs with perverse incentives (though the perverse incentive at each cliff tends to be less). Another solution is to introduce rules that attempt to identify people who are "abusing the system" and punish them. So, for example, you can only be on welfare for a limited time because people got outraged that single mothers wound up on welfare for a long time. However those single mothers were acting that was in part because they were better off on welfare looking after their own kids than they were in a low end job and paying for daycare. Stereotypically the first type of solution is characteristic of Democrats and the second of Republicans. But the truth is that both parties do a lot of both solutions.
福利门槛缺陷人尽皆知却几十年不改，是政治失灵的标志
至少在我看来，TANF、Medicaid、CHIP 等项目中的不连续点，是政治失灵最明显的标志之一。这些缺陷是坏事这一点完全不涉及党派立场——所有人都应该认同它们毫无道理、会误导行为激励。然而尽管从设立之初就不断被讨论，这些缺陷依然存在了几十年。
kauffj查看英文原文
At least to me, the discontinuities in things like TANF, Medicaid, CHIP, etc. are some of the greatest signs of political dysfunction. There's nothing remotely partisan about these being a bad thing. _Everyone_ should agree that these make no sense and mis-incentivize behavior. Yet these flaws remain for decades despite being known and discussed for approximately the entirety of their existence.
国际象棋等级分分布每 100 分出现尖峰，是玩家追逐整数门槛的又一例证
下快棋的人（大概）会执着于把 Elo 等级分提升到下一个 100 分区间，导致等级分分布每 100 分出现一个尖峰。
maxmcd查看英文原文
People playing speed chess (presumably) get fixated on improving their Elo rating by the next 100 point span, leading to spikes every 100 rating points in the distribution: https://lichess.org/stat/rating/distribution/bullet
交友网站自报身高整体虚报 2 英寸，是自报数据围绕门槛失真的例子
OKCupid 有一张男性自报身高的图表：整体比平均身高向右偏移了 2 英寸，同时在常见的身高峰值 5 英尺 10 英寸附近略微变平。虽然不像这篇文章里的图那么明显，但仍然值得注意。
lkbm查看英文原文
OKCupid has a graph of reported height for men[0]. It's both shifted 2 inches to the right of average, but also slightly flattened at the normal peak of 5'10". It's not nearly as pronounced as the graphs in this post, but it's still notable. [0] https://theblog.okcupid.com/the-big-lies-people-tell-in-online-dating-a9e3990d6ae2
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