协同翻译(十五)Don’t Blink! The Hazards of Confidence | 别眨眼!自信的危害 - 作者:Daniel Kahneman
点击可看翻译过程(耐心等候10秒)---> http://translation_group.titanpad.com/ep/pad/view/ro.5bMmONkEW/rev.0
本期的翻译文章是诺奖得主 Danial Kahneman "Don't Blink! The Hazards of Confidence".
Kahneman 是一位颇神奇的科学家。他的本行是心理学,但是却获得了2002年诺贝尔经济学奖。他从心理学的角度,开辟了一门新的经济学领域叫做 “行为经济学” (behavioral economics)。
本文写于2011年。其中 Kahneman 介绍“自信”(或者说“过度自信”)的坏处。本文不仅介绍了行为经济学研究的一个经典结果,同时对各位在自己生活中或也有启发。
对 Kahneman 的研究领域感兴趣的朋友可以看他的新书《快思慢想》(Thinking, fast and slow) http://book.douban.com/subject/20280796/
此文章为豆友协同翻译而成,请勿做商业用途,违者必究!
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译者
@峰哥何峰 这次是 Kahneman 的长文;特别感谢@猩猩君 的贡献!
@ZOYYE
@Summer
@寂静海
@永不分狸
@猩猩君
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Original link: http://www.nytimes.com/2011/10/23/magazine/dont-blink-the-hazards-of-confidence.html?_r=0&pagewanted=print
October 19, 2011
Don’t Blink! The Hazards of Confidence By DANIEL KAHNEMAN
别眨眼!自信的危害 作者:Daniel Kahneman
Many decades ago I spent what seemed like a great deal of time under a scorching sun, watching groups of sweaty soldiers as they solved a problem. I was doing my national service in the Israeli Army at the time. I had completed an undergraduate degree in psychology, and after a year as an infantry officer, I was assigned to the army’s Psychology Branch, where one of my occasional duties was to help evaluate candidates for officer training. We used methods that were developed by the British Army in World War II.
几十年前,我在烈日下花了似乎有很长时间,观察一群挥汗的士兵解决一个问题。当时我在以色列的部队里服兵役。此前我拿到了心理学学士学位,并在一年后成为了一名陆军士官。我被委派到了心理学分部,偶尔我会参与在军官培训中评测应征者。我们采用的方法由二战时的英国军队开发。
One test, called the leaderless group challenge, was conducted on an obstacle field. Eight candidates, strangers to one another, with all insignia of rank removed and only numbered tags to identify them, were instructed to lift a long log from the ground and haul it to a wall about six feet high. There, they were told that the entire group had to get to the other side of the wall without the log touching either the ground or the wall, and without anyone touching the wall. If any of these things happened, they were to acknowledge it and start again.
其中一个测试,叫做“无领导团体挑战”,是在一个有障碍物的场地上进行的。八个选手,互相不认识,军衔标记都被摘除,只用编号的标签来识别。他们的任务是要举起一截长圆木并运到一面大约六英尺高的墙边。在那儿,他们又被告知整个小组必须抵达墙的另一边,圆木既不能接触地面又不能接触墙,而且每个人也都不能接触墙。如果不允许的接触发生了,他们就要报告并重新开始。
A common solution was for several men to reach the other side by crawling along the log as the other men held it up at an angle, like a giant fishing rod. Then one man would climb onto another’s shoulder and tip the log to the far side. The last two men would then have to jump up at the log, now suspended from the other side by those who had made it over, shinny their way along its length and then leap down safely once they crossed the wall. Failure was common at this point, which required starting over.
常见的解决方法是像一个巨大的鱼竿一般,他们中的几个人以某个角度举起原木,其它人沿着原木爬到另一端。然后,一个人爬到另一个人肩膀上并使原木向远侧倾斜。最后的两个人只能跳上原木,已经转移到对面的人此时使原木悬空固定,这两个人用自己的方式顺着爬过去,然后当他们越过墙时所有人安全地一跃而下。这个关键点非常容易失败,失败的话也就只好从新开始。
As a colleague and I monitored the exercise, we made note of who took charge, who tried to lead but was rebuffed, how much each soldier contributed to the group effort. We saw who seemed to be stubborn, submissive, arrogant, patient, hot-tempered, persistent or a quitter. We sometimes saw competitive spite when someone whose idea had been rejected by the group no longer worked very hard. And we saw reactions to crisis: who berated a comrade whose mistake caused the whole group to fail, who stepped forward to lead when the exhausted team had to start over. Under the stress of the event, we felt, each man’s true nature revealed itself in sharp relief.
在我和一个同事一起观测这个活动时,我们注意到谁是主导者,谁试图领导大家但是被断然拒绝,每个士兵对集体努力的结果付出多少。我们观察到了哪些人是顽固的,哪些是顺从的,哪些是傲慢的,哪些是有耐心的,哪些是脾气暴躁的,哪些是有持续性的或是半途而废的。虽然团队中会出现龃龉:有人因为自己的想法被否定,而不再非常努力。并且,我们看到面对危机的反应:哪些人会斥责造成团队失败的同伴,哪些人会在不得不从新开始时挺身而出,带领已经疲惫的团队。我们认为,该事件的压力下,每个人的真实本性都清晰地显露了出来。
After watching the candidates go through several such tests, we had to summarize our impressions of the soldiers’ leadership abilities with a grade and determine who would be eligible for officer training. We spent some time discussing each case and reviewing our impressions. The task was not difficult, because we had already seen each of these soldiers’ leadership skills. Some of the men looked like strong leaders, others seemed like wimps or arrogant fools, others mediocre but not hopeless. Quite a few appeared to be so weak that we ruled them out as officer candidates. When our multiple observations of each candidate converged on a coherent picture, we were completely confident in our evaluations and believed that what we saw pointed directly to the future. The soldier who took over when the group was in trouble and led the team over the wall was a leader at that moment. The obvious best guess about how he would do in training, or in combat, was that he would be as effective as he had been at the wall. Any other prediction seemed inconsistent with what we saw.
在候选人经过几个这样的测试之后,我们用等级来对每个士兵的领导能力进行总结,并决定谁有资格进行领事官训练。我们花时间讨论每个案子,回顾我们的印象。这个任务并不难,因为我们已经看到这些士兵的领导能力。在他们中,一些人看起来像是强有力的领导者,一些人则像懦夫或自大的傻瓜,一些人则平庸却不绝望。相当多的人表现的很懦弱,我们在选候补军官时将他们排除在外。当我们将每名候选人集中在一个连贯的画面上进行多重观察时,我们完全信任我们的评估结果,并且确信我们所观察到的对未来有着直接地预示作用。当团队遇到困难的时刻,接管并带领团队越过墙的那个士兵就是一个领导者。对他在训练或战斗中将会如何去做的最佳猜测,明显是他会像在越墙时一样有效的进行行动。而任何其他的预测似乎与我们所看到的不一致。
Because our impressions of how well each soldier performed were generally coherent and clear, our formal predictions were just as definite. We rarely experienced doubt or conflicting impressions. We were quite willing to declare: “This one will never make it,” “That fellow is rather mediocre, but should do O.K.” or “He will be a star.” We felt no need to question our forecasts, moderate them or equivocate. If challenged, however, we were fully prepared to admit, “But of course anything could happen.”
因为普遍来说我们对每个士兵表现优劣的印象都是很一致很明确的,我们对他们的正式预测也是同样清晰明确的。我们很少会有疑问或者互相矛盾的印象,我们都很愿意断言: "这个士兵永远达不到我们的要求," "那位仁兄太平庸了,但应该还是可以的." 或者"他注定成为明星." 我们觉得没有必要对我们的预测产生疑问,进行修正或者含糊其辞。但如果我们的预测被人疑问挑战了,我们也都愿意承认,"但是当然这事谁也说不准."
We were willing to make that admission because, as it turned out, despite our certainty about the potential of individual candidates, our forecasts were largely useless. The evidence was overwhelming. Every few months we had a feedback session in which we could compare our evaluations of future cadets with the judgments of their commanders at the officer-training school. The story was always the same: our ability to predict performance at the school was negligible. Our forecasts were better than blind guesses, but not by much.
我们愿意这样承认是因为,往往尽管我们对每个候选人的潜力很确定,我们的预测很大程度上是完全没用的。证据是压倒性的。每隔几个月我们都会有一个回馈环节, 这时我们可以将我们对这些未来的士官的评估和军官训练学校的指挥官的判断进行对比。结局总是一成不变的:我们预测这些士官在学校表现的能力几乎是可以忽略的。我们的预测比蒙着眼睛瞎懵强些,但是也不会强到哪里去。
We were downcast for a while after receiving the discouraging news. But this was the army. Useful or not, there was a routine to be followed, and there were orders to be obeyed. Another batch of candidates would arrive the next day. We took them to the obstacle field, we faced them with the wall, they lifted the log and within a few minutes we saw their true natures revealed, as clearly as ever. The dismal truth about the quality of our predictions had no effect whatsoever on how we evaluated new candidates and very little effect on the confidence we had in our judgments and predictions.
在得知这一消息之后我们着实沮丧了一段时间,但在军队里么,不管有效还是无效,还是要遵守传统和规矩的。第二天来了新的一批候选人。我们带他们到障碍测试的场地,仍然让他们面对着那堵墙,举起了木头,而且和原来一样,我们很快就看到了他们的真实性格。那个令人沮丧的事实并没有影响到我们对新候选人的评判,同样也没有影响到我们对自己判断和预测的信心。
I thought that what was happening to us was remarkable. The statistical evidence of our failure should have shaken our confidence in our judgments of particular candidates, but it did not. It should also have caused us to moderate our predictions, but it did not. We knew as a general fact that our predictions were little better than random guesses, but we continued to feel and act as if each particular prediction was valid. I was reminded of visual illusions, which remain compelling even when you know that what you see is false. I was so struck by the analogy that I coined a term for our experience: the illusion of validity.
我想发生在我们身上的变化是值得注意的。在我们对特定的候选人的判断中,我们失败的统计学证据本来应该挫伤我们的自信,但是实际上没有。虽然我们知道这个简单的道理:我们的预测基本上比胡乱的猜想好不了多少,但是我们还是把每一个特定的预测都假设成是有效的,并继续去感知和测试那些候选人。这让我想起了视觉幻象,它会使你在知道自己所见的是假象的情况下依然强迫你去观察。这种类似的经历使我深受打击,以至于我杜撰了一个关于这次经历的术语:有效性幻象。
I had discovered my first cognitive fallacy.
我发现了我的第一个认知谬误。
Decades later, I can see many of the central themes of my thinking about judgment in that old experience. One of these themes is that people who face a difficult question often answer an easier one instead, without realizing it. We were required to predict a soldier’s performance in officer training and in combat, but we did so by evaluating his behavior over one hour in an artificial situation. This was a perfect instance of a general rule that I call WYSIATI, “What you see is all there is.” We had made up a story from the little we knew but had no way to allow for what we did not know about the individual’s future, which was almost everything that would actually matter. When you know as little as we did, you should not make extreme predictions like “He will be a star.” The stars we saw on the obstacle field were most likely accidental flickers, in which a coincidence of random events — like who was near the wall — largely determined who became a leader. Other events — some of them also random — would determine later success in training and combat.
You may be surprised by our failure: it is natural to expect the same leadership ability to manifest itself in various situations. But the exaggerated expectation of consistency is a common error. We are prone to think that the world is more regular and predictable than it really is, because our memory automatically and continuously maintains a story about what is going on, and because the rules of memory tend to make that story as coherent as possible and to suppress alternatives. Fast thinking is not prone to doubt.
几十年后,我能理解许多以我的那种旧经验作出判断的见解的中心主题。主题之一是,当面对一个困难的问题的时候,人们经常在无意识的情况下回答一个更简单的来代替。我们被要求预测士兵在军官培训中和在战斗中的表现,但我们的预测仅通过评价他在一小时里在人工场景下的表现。这是个普适规则的最好实例,我把它叫作“WYSIATI”,(What you see is all there is)一叶障目。我们从自己所知的冰山一角里编出个故事,却一点也不考虑到我们不确定的个体的未来,那才几乎是真正最重要的全部。当你的了解和我们一样少时,你不应该作出像“他会是个明星”这样极端的预测。那些我们看到的在障碍物场地上的明星很可能只是偶然闪烁,随机事件里的一个巧合,就像谁离墙近谁就成了领导者——很大程度上决定了谁是领导者。其它一些同样随机的事件,会决定后来在军官培训和战斗中的胜出。
你可能惊讶于我们的失败:期待相同的领导力在各种情况下,这很自然。但是过分的一致性(一成不变的)预期是个常见错误。我们更倾向于认为这个世界比她实质上的更规律和可预期,因为我们的记忆会无意识并连续不断地维持一个正在发生的故事,而且记忆的规则趋向于使故事尽可能连贯一致来抑制(故事的)其他可能。快速思考不容易产生怀疑。
The confidence we experience as we make a judgment is not a reasoned evaluation of the probability that it is right. Confidence is a feeling, one determined mostly by the coherence of the story and by the ease with which it comes to mind, even when the evidence for the story is sparse and unreliable. The bias toward coherence favors overconfidence. An individual who expresses high confidence probably has a good story, which may or may not be true.
我们做决定时候体验到的自信,并不是一个基于概率的有理有据的评价。自信是一个赶脚(译者:“赶脚”卖萌挺好的啊)(另一译者:好吧,我也改回赶脚了。。我太不会卖萌了!),主要被叙述故事的通顺和想到这故事的从容而决定,即使对这故事正确性的证据是又少又不可靠。对通顺的偏好容易引发过度自信。一个非常自信的人心里大概有一个(可能真也可能假的)好故事。
I coined the term “illusion of validity” because the confidence we had in judgments about individual soldiers was not affected by a statistical fact we knew to be true — that our predictions were unrelated to the truth. This is not an isolated observation. When a compelling impression of a particular event clashes with general knowledge, the impression commonly prevails. And this goes for you, too. The confidence you will experience in your future judgments will not be diminished by what you just read, even if you believe every word.
我发明了“illusion of validity”这个术语是因为我们对于士兵潜力判断的自信心,并没有被我们明知是真相的统计学事实影响到 --- 我们的预测和真相是毫无联系的。这不是一个孤立的观察结果。当对某个特定事件的强力印象与常识发生碰撞,那种强力印象通常会获胜。对正在读这篇文章的您来说也是如此。你未来下判断时的自信心[强力印象]并不会被你刚刚读到的内容[已成为你"常识"的一部分]而削弱,虽然你相信你读到的每个字。
I first visited a Wall Street firm in 1984. I was there with my longtime collaborator Amos Tversky, who died in 1996, and our friend Richard Thaler, now a guru of behavioral economics. Our host, a senior investment manager, had invited us to discuss the role of judgment biases in investing. I knew so little about finance at the time that I had no idea what to ask him, but I remember one exchange. “When you sell a stock,” I asked him, “who buys it?” He answered with a wave in the vague direction of the window, indicating that he expected the buyer to be someone else very much like him. That was odd: because most buyers and sellers know that they have the same information as one another, what made one person buy and the other sell? Buyers think the price is too low and likely to rise; sellers think the price is high and likely to drop. The puzzle is why buyers and sellers alike think that the current price is wrong.
1984年我第一次拜访了一家华尔街公司。我是和我的长期合作者Amos Tversky一起去的,他在1996年去世了,还有我们的朋友Richard Thaler,现在是行为经济学专家。我们的主持,一个高级投资经理人,邀请我们来讨论判断偏差在投资中的角色。那时候我对金融知之甚少完全不知道问他什么,但是我记得其中一个交流。”在你卖一个股票的时候” 我问他,”买家是谁?” 他朝着大概窗户的方向挥了挥手并回答,他期望买家是和他自己非常相似的人。这很奇怪:因为大多数卖家和买家都知道他们拥有相同的信息,是什么使其中一人买另一人卖呢?买家认为价格太低有可能会升值;卖家爱认为价格太高有可能会下跌。这个难题就是为什么买家和买家在市价不合理这件事上会所见略同。
Most people in the investment business have read Burton Malkiel’s wonderful book “A Random Walk Down Wall Street.” Malkiel’s central idea is that a stock’s price incorporates all the available knowledge about the value of the company and the best predictions about the future of the stock. If some people believe that the price of a stock will be higher tomorrow, they will buy more of it today. This, in turn, will cause its price to rise. If all assets in a market are correctly priced, no one can expect either to gain or to lose by trading.
大多数做投资业务的人都读过Burton Malkiel’s的著作《漫步华尔街》。 Malkiel的中心思想是,一只股票的价格体现在发行公司的价值以及对该股票未来的最好预期相关的所有可知消息里。如果一部分人相信股票明天会升值,他们今天会更多地买入。这相应的就会造成股价地上涨。如果市场里的所有资产都被正确地估价,就没有人能预期交易会是盈还是亏了。
We now know, however, that the theory is not quite right. Many individual investors lose consistently by trading, an achievement that a dart-throwing chimp could not match. The first demonstration of this startling conclusion was put forward by Terry Odean, a former student of mine who is now a finance professor at the University of California, Berkeley.
然而,我们现在知道这个理论并不正确。许多个人投资者在交易中始终赔钱,而这个结果还不如黑猩猩扔飞镖的成绩。对于这个令人吃惊的结论的第一个证明由我以前的学生,现在在加州大学伯克利分校任教的金融学教授Terry Odean提出。
Odean analyzed the trading records of 10,000 brokerage accounts of individual investors over a seven-year period, allowing him to identify all instances in which an investor sold one stock and soon afterward bought another stock. By these actions the investor revealed that he (most of the investors were men) had a definite idea about the future of two stocks: he expected the stock that he bought to do better than the one he sold.
Odean教授分析了10000名个人投资者的证券账户七年间的交易记录,这使得他可以找出一个投资者在卖掉一只股票后马上买入另一只股票的所有事例。通过这些行为,投资者显示出他(大多数投资者是男性)对于两只股票的未来有确定的看法:他预计他买的那只股票会比他卖掉的那只股票在未来表现的更好。
To determine whether those appraisals were well founded, Odean compared the returns of the two stocks over the following year. The results were unequivocally bad. On average, the shares investors sold did better than those they bought, by a very substantial margin: 3.3 percentage points per year, in addition to the significant costs of executing the trades. Some individuals did much better, others did much worse, but the large majority of individual investors would have done better by taking a nap rather than by acting on their ideas. In a paper titled “Trading Is Hazardous to Your Wealth,” Odean and his colleague Brad Barber showed that, on average, the most active traders had the poorest results, while those who traded the least earned the highest returns. In another paper, “Boys Will Be Boys,” they reported that men act on their useless ideas significantly more often than women do, and that as a result women achieve better investment results than men.
为了确定这些估价是否正确,Odean教授比较了两只股票在以后的年份里的回报。结果十分糟糕。平均下来,投资者卖掉的那些股份表现上大幅优于他们买的那些股份,每年高达3.3%,与此同时还没有算上交易股票所产生的巨大费用。一些人的确做得业绩更好,一些人做得更差,但是绝大多数投资者都可以做得更好,如果他们只是打个盹而不是根据他们的想法进行股票交易。在一篇标题为“交易行为使你的财富面临危险”的论文中,Odean教授和他的同事Brad Barber提出,平均下来。最活跃的交易者有着最差的结果,然而那些进行了最少交易的人得到了最高的回报。在另一篇论文“男孩将会成为男人”中,他们说,男人比女人更经常地按照他们毫无用处的想法行事,所以,女人比男人有更好的投资回报。
Of course, there is always someone on the other side of a transaction; in general, it’s a financial institution or professional investor, ready to take advantage of the mistakes that individual traders make. Further research by Barber and Odean has shed light on these mistakes. Individual investors like to lock in their gains; they sell “winners,” stocks whose prices have gone up, and they hang on to their losers. Unfortunately for them, in the short run going forward recent winners tend to do better than recent losers, so individuals sell the wrong stocks. They also buy the wrong stocks. Individual investors predictably flock to stocks in companies that are in the news. Professional investors are more selective in responding to news. These findings provide some justification for the label of “smart money” that finance professionals apply to themselves.
当然,总有人处在一个交易行为的另一端;大体上来说,总是一个金融机构或是一名专业投资者准备利用那些个人投资者犯下的错误。Barber教授和Odean教授更进一步的研究聚焦于于个人投资者犯下的错误。个人投资者喜欢锁定他们的收益:他们卖出那些股价升高的“赢家”股票,并且坚守那些“失败者”股票。对于他们来说,很不幸的是,在短期上,近期的“赢家”往往比近期的“失败者”表现得更好,所以个人投资者卖错了股票。他们也买错股票。个人投资者可预见地涌向那些被报导公司的股票。专业投资者往往是有选择性的对于新闻做出回应。这些发现为金融专家们给自己贴的标签“聪明钱”提供了证明。
Although professionals are able to extract a considerable amount of wealth from amateurs, few stock pickers, if any, have the skill needed to beat the market consistently, year after year. The diagnostic for the existence of any skill is the consistency of individual differences in achievement. The logic is simple: if individual differences in any one year are due entirely to luck, the ranking of investors and funds will vary erratically and the year-to-year correlation will be zero. Where there is skill, however, the rankings will be more stable. The persistence of individual differences is the measure by which we confirm the existence of skill among golfers, orthodontists or speedy toll collectors on the turnpike.
尽管专家们可以从业余投资者那里获得很大一笔财富,很少有人(如果有的话)有能力持续地、一年又一年地战胜市场。任何技术,其存在的特征是个体成就差异的稳定性。背后的逻辑很简单:如果个体成就上的差异在某一年中完全是由于运气造成的,那么投资者和基金的排名每年都会不规律地改变,而且每年排名的相关性将会是零。但是,如果拥有技术,排名就会更加稳定。个体成就上差异的持续正是我们肯定高尔夫球手,整牙医师以及在收费高速路口快速收费的收费员拥有技术的方法。(这段觉得好别扭。不知道该怎么改。。大家帮帮忙吧)
Mutual funds are run by highly experienced and hard-working professionals who buy and sell stocks to achieve the best possible results for their clients. Nevertheless, the evidence from more than 50 years of research is conclusive: for a large majority of fund managers, the selection of stocks is more like rolling dice than like playing poker. At least two out of every three mutual funds underperform the overall market in any given year.
共同基金通常是由非常有经验的并且十分勤勉的专业人士来运营的,他们买卖股票以为客户带来最好的结果。然而,从超过50年的研究中得到的证据得出一个非常确定的结论:对于大多数基金经理来说,选择股票与其说是打扑克,更像是掷色子。至少三分之二的共同基金都在任何一个特定年份中跑输整体市场。
More important, the year-to-year correlation among the outcomes of mutual funds is very small, barely different from zero. The funds that were successful in any given year were mostly lucky; they had a good roll of the dice. There is general agreement among researchers that this is true for nearly all stock pickers, whether they know it or not — and most do not. The subjective experience of traders is that they are making sensible, educated guesses in a situation of great uncertainty. In highly efficient markets, however, educated guesses are not more accurate than blind guesses.
更重要的是,共同基金每年的投资结果相关性非常小,接近于零。在特定一年中成功的基金原因大多是运气好;他们恰巧赶上色子滚得好(滚得好。。。不对劲)。研究者们关于挑选股票的人达成了一个共识,无论他们中大多数是否知道——大多数人不知道。交易者的主观经验是他们在一个具有高度不确定性的环境中进行着明智的(sensible在这里应该怎么翻译?感觉明智不太对。)、有根据的猜测。然而,在一个高效的市场中,有根据的猜测并不比瞎蒙更准确。
Some years after my introduction to the world of finance, I had an unusual opportunity to examine the illusion of skill up close. I was invited to speak to a group of investment advisers in a firm that provided financial advice and other services to very wealthy clients. I asked for some data to prepare my presentation and was granted a small treasure: a spreadsheet summarizing the investment outcomes of some 25 anonymous wealth advisers, for eight consecutive years. The advisers’ scores for each year were the main determinant of their year-end bonuses. It was a simple matter to rank the advisers by their performance and to answer a question: Did the same advisers consistently achieve better returns for their clients year after year? Did some advisers consistently display more skill than others?
在我接触了金融世界一些年后,我获得一个可以近距离研究对于技术的错觉的机会。我受邀去一个为非常富有的客户提供理财咨询和其他服务的公司,向一群投资顾问做报告。我要来了一些数据用来准备我的报告,于此同时得到了一小笔财富:一个总结了25位匿名的投资顾问连续八年的投资业绩的电子表格。投资顾问们每年的业绩是他们年终奖金的主要决定因素。把投资顾问按他们的业绩进行排名并回答一个问题变成了很简单的事情。同一名顾问是否可以连续地每年都为客户带去更高的回报?一些顾问是不是可以持续地相较于其他人展现出更多技术?
To find the answer, I computed the correlations between the rankings of advisers in different years, comparing Year 1 with Year 2, Year 1 with Year 3 and so on up through Year 7 with Year 8. That yielded 28 correlations, one for each pair of years. While I was prepared to find little year-to-year consistency, I was still surprised to find that the average of the 28 correlations was .01. In other words, zero. The stability that would indicate differences in skill was not to be found. The results resembled what you would expect from a dice-rolling contest, not a game of skill.
为了寻找答案,我计算了不同年份中顾问的排名的相关性,把第一年的排名与第二年的排名对比,把第一年的排名与第三年的排名对比,直到把第七年的排名与第八年的排名进行对比。就这样,产生了28个相关性数据,每一个对应一组年份。尽管我对于发现非常小的年与年之间的相关性有所预期,我仍然很惊讶地发现28组数据的相关性平均数只有0.01。换句话说,就是零。可以用来表示技术差异的稳定性并没有被发现。这个结果就跟你能在掷色子比赛中期待的一样,这压根不是一个有关技术的比赛。
No one in the firm seemed to be aware of the nature of the game that its stock pickers were playing. The advisers themselves felt they were competent professionals performing a task that was difficult but not impossible, and their superiors agreed. On the evening before the seminar, Richard Thaler and I had dinner with some of the top executives of the firm, the people who decide on the size of bonuses. We asked them to guess the year-to-year correlation in the rankings of individual advisers. They thought they knew what was coming and smiled as they said, “not very high” or “performance certainly fluctuates.” It quickly became clear, however, that no one expected the average correlation to be zero.
公司里似乎没有人意识到他们的股票挑选者所玩的游戏的本质。那些顾问他们自己认为他们是一群有能力的专家进行着一项十分困难但是并不是完全不可能的任务,他们的上级也这么认为。在报告会的前一天晚上,Richard Thaler和我一起与公司里的高级主管人员共进了晚餐,正是这些高级主管人员决定奖金的多少。我们请他们猜投资顾问的排名在历年的相关性。他们认为他们知道将要发生什么,笑着说:“不是很高”或者“表现肯定会有波动”。然而,事实很快变得明朗起来,根本没有人预料到平均相关性会是零。
What we told the directors of the firm was that, at least when it came to building portfolios, the firm was rewarding luck as if it were skill. This should have been shocking news to them, but it was not. There was no sign that they disbelieved us. How could they? After all, we had analyzed their own results, and they were certainly sophisticated enough to appreciate their implications, which we politely refrained from spelling out. We all went on calmly with our dinner, and I am quite sure that both our findings and their implications were quickly swept under the rug and that life in the firm went on just as before. The illusion of skill is not only an individual aberration; it is deeply ingrained in the culture of the industry. Facts that challenge such basic assumptions — and thereby threaten people’s livelihood and self-esteem — are simply not absorbed. The mind does not digest them. This is particularly true of statistical studies of performance, which provide general facts that people will ignore if they conflict with their personal experience.
我们告诉公司的主管们的是,至少在建立投资组合时,公司是在把运气当做技术来奖励。这本他们来说本应是令人震惊的消息,但事实上却不是。并没有任何迹象表明他们不相信我们。他们为什么会这样?毕竟,我们分析的是他们自己的业绩,他们也老练到足以领会对他们的暗示,鉴于礼貌的原因,我们克制住自己,并没有说出来。(这句appreciate their implications指什么?)我们继续平静地进行着我们的晚餐,我十分确定我们的发现和他们的暗示很快地就被回避了,在公司里的生活继续像以前一样进行着。对于技术的错觉不仅仅是个人的失常,它是根深蒂固在行业的文化中的。那些挑战最基本的假设,进而威胁到人们的生计和自尊的事实,轻易地被忽略了。大脑并不处理它们。这在关于表现的统计学研究中尤为突出,这些研究为人们提供一些事实,如果事实与人们自身经验相冲突,人们就会忽略它们。
The next morning, we reported the findings to the advisers, and their response was equally bland. Their personal experience of exercising careful professional judgment on complex problems was far more compelling to them than an obscure statistical result. When we were done, one executive I dined with the previous evening drove me to the airport. He told me, with a trace of defensiveness, “I have done very well for the firm, and no one can take that away from me.” I smiled and said nothing. But I thought, privately: Well, I took it away from you this morning. If your success was due mostly to chance, how much credit are you entitled to take for it?
第二天早晨,我们向顾问们汇报了我们的发现,而他们同样反应的平淡无奇. 在复杂的问题上,他们的私人经验是小心的给予专业意见,对他们来说这个做法要比相信晦涩的统计数据结果重要的多。当我们结束时,一个前一晚和我一起吃晚餐的主管开车送我去机场. 他带着一丝抵触的语气同我说,"一直以来我对公司尽心尽力,没有人可以否定我的工作。" 我笑了笑没有说任何话。但是私下里我想:真可惜,我今天早晨已经否定了你的工作。如果你工作的成功大部分是取决于运气,你有多少资格向公司邀功呢?
We often interact with professionals who exercise their judgment with evident confidence, sometimes priding themselves on the power of their intuition. In a world rife with illusions of validity and skill, can we trust them? How do we distinguish the justified confidence of experts from the sincere overconfidence of professionals who do not know they are out of their depth? We can believe an expert who admits uncertainty (but cannot take expressions of high confidence at face value)Help!!. As I first learned on the obstacle field, people come up with coherent stories and confident predictions even when they know little or nothing. Overconfidence arises because people are often blind to their own blindness.
我们经常与专家们互相影响,他们带着显而易见的自信运用自己的判断,有时对自己直觉的力量引以为傲。在这个充斥着有效度和技巧幻觉的世界里,我们能信任他们吗?要怎么才能从那些明明力所不及、真挚但过度自信的专家里,分辨出那些恰当自信的专家?我们能相信一个承认不确定性的专家,但不能以高度自信表情的表面现象取人。我第一次在障碍物场地上学习到,即使所知甚少,人们还是会想出连贯的故事和作出自信的预测。自负的出现是因为人们无知于自己的无知
True intuitive expertise is learned from prolonged experience with good feedback on mistakes. You are probably an expert in guessing your spouse’s mood from one word on the telephone; chess players find a strong move in a single glance at a complex position; and true legends of instant diagnoses are common among physicians. To know whether you can trust a particular intuitive judgment, there are two questions you should ask: Is the environment in which the judgment is made sufficiently regular to enable predictions from the available evidence? The answer is yes for diagnosticians, no for stock pickers. Do the professionals have an adequate opportunity to learn the cues and the regularities? The answer here depends on the professionals’ experience and on the quality and speed with which they discover their mistakes. Anesthesiologists have a better chance to develop intuitions than radiologists do. Many of the professionals we encounter easily pass both tests, and their off-the-cuff judgments deserve to be taken seriously. In general, however, you should not take assertive and confident people at their own evaluation unless you have independent reason to believe that they know what they are talking about. Unfortunately, this advice is difficult to follow: overconfident professionals sincerely believe they have expertise, act as experts and look like experts. You will have to struggle to remind yourself that they may be in the grip of an illusion.
真实直观的专业知识的习得依赖于从错误中获得好的反馈的长期经验。从电话交谈的一句话里猜测出自己配偶的情绪,在那方面你很可能是个专家;在复杂的棋盘上的一个眼神,国际象棋选手就能发现一步极好的棋;医师真实的传说般瞬间作出诊断也很正常。要知道自己是否能相信一个特定的直觉判断,你要问两个问题:1.做出判断的环境是否足够规律,使从现有证据里作出的预言成为可能?对于诊断医生来说答案是肯定的,对于拣股者是否定的。2.专家是否有充分的机会获悉线索和规律?回答取决于专家的经验,和他们发觉自己错误的质量和速度。麻醉医师比放射科医师有更好的机会开发自己的直觉。我们遇到的许多专家轻松地通过了这两个问题的测试,他们的即兴判断就值得被严肃看待。但一般来说,你不应采信来自独断自信的人他们自己的评估,除非你有能独立判断的理由来相信,他们熟悉他们所谈论的。不幸的是,这条忠告很难被遵从。自负的专家由衷地相信自己有最专业的知识,做起来或者看上去都像个行家。你必须努力提醒自己,他们可能陷入了自己错误的信仰里。
Daniel Kahneman is emeritus professor of psychology and of public affairs at Princeton University and a winner of the 2002 Nobel Prize in Economics. This article is adapted from his book “Thinking, Fast and Slow,” out this month from Farrar, Straus & Giroux.
Editor: Dean Robinson
Daniel Kahneman是普林斯顿大学心理学和公共事务学的退休教授,他也是2002年诺贝尔经济学奖的获奖者。这篇文章是从他的著作《思考,快与慢》(http://book.douban.com/subject/10785583/) 改编而来的,这本书将于本月由Farrar, Straus & Giroux出版。
编辑:Dean Robinson
本期的翻译文章是诺奖得主 Danial Kahneman "Don't Blink! The Hazards of Confidence".
Kahneman 是一位颇神奇的科学家。他的本行是心理学,但是却获得了2002年诺贝尔经济学奖。他从心理学的角度,开辟了一门新的经济学领域叫做 “行为经济学” (behavioral economics)。
本文写于2011年。其中 Kahneman 介绍“自信”(或者说“过度自信”)的坏处。本文不仅介绍了行为经济学研究的一个经典结果,同时对各位在自己生活中或也有启发。
对 Kahneman 的研究领域感兴趣的朋友可以看他的新书《快思慢想》(Thinking, fast and slow) http://book.douban.com/subject/20280796/
此文章为豆友协同翻译而成,请勿做商业用途,违者必究!
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译者
@峰哥何峰 这次是 Kahneman 的长文;特别感谢@猩猩君 的贡献!
@ZOYYE
@Summer
@寂静海
@永不分狸
@猩猩君
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Original link: http://www.nytimes.com/2011/10/23/magazine/dont-blink-the-hazards-of-confidence.html?_r=0&pagewanted=print
October 19, 2011
Don’t Blink! The Hazards of Confidence By DANIEL KAHNEMAN
别眨眼!自信的危害 作者:Daniel Kahneman
Many decades ago I spent what seemed like a great deal of time under a scorching sun, watching groups of sweaty soldiers as they solved a problem. I was doing my national service in the Israeli Army at the time. I had completed an undergraduate degree in psychology, and after a year as an infantry officer, I was assigned to the army’s Psychology Branch, where one of my occasional duties was to help evaluate candidates for officer training. We used methods that were developed by the British Army in World War II.
几十年前,我在烈日下花了似乎有很长时间,观察一群挥汗的士兵解决一个问题。当时我在以色列的部队里服兵役。此前我拿到了心理学学士学位,并在一年后成为了一名陆军士官。我被委派到了心理学分部,偶尔我会参与在军官培训中评测应征者。我们采用的方法由二战时的英国军队开发。
One test, called the leaderless group challenge, was conducted on an obstacle field. Eight candidates, strangers to one another, with all insignia of rank removed and only numbered tags to identify them, were instructed to lift a long log from the ground and haul it to a wall about six feet high. There, they were told that the entire group had to get to the other side of the wall without the log touching either the ground or the wall, and without anyone touching the wall. If any of these things happened, they were to acknowledge it and start again.
其中一个测试,叫做“无领导团体挑战”,是在一个有障碍物的场地上进行的。八个选手,互相不认识,军衔标记都被摘除,只用编号的标签来识别。他们的任务是要举起一截长圆木并运到一面大约六英尺高的墙边。在那儿,他们又被告知整个小组必须抵达墙的另一边,圆木既不能接触地面又不能接触墙,而且每个人也都不能接触墙。如果不允许的接触发生了,他们就要报告并重新开始。
A common solution was for several men to reach the other side by crawling along the log as the other men held it up at an angle, like a giant fishing rod. Then one man would climb onto another’s shoulder and tip the log to the far side. The last two men would then have to jump up at the log, now suspended from the other side by those who had made it over, shinny their way along its length and then leap down safely once they crossed the wall. Failure was common at this point, which required starting over.
常见的解决方法是像一个巨大的鱼竿一般,他们中的几个人以某个角度举起原木,其它人沿着原木爬到另一端。然后,一个人爬到另一个人肩膀上并使原木向远侧倾斜。最后的两个人只能跳上原木,已经转移到对面的人此时使原木悬空固定,这两个人用自己的方式顺着爬过去,然后当他们越过墙时所有人安全地一跃而下。这个关键点非常容易失败,失败的话也就只好从新开始。
As a colleague and I monitored the exercise, we made note of who took charge, who tried to lead but was rebuffed, how much each soldier contributed to the group effort. We saw who seemed to be stubborn, submissive, arrogant, patient, hot-tempered, persistent or a quitter. We sometimes saw competitive spite when someone whose idea had been rejected by the group no longer worked very hard. And we saw reactions to crisis: who berated a comrade whose mistake caused the whole group to fail, who stepped forward to lead when the exhausted team had to start over. Under the stress of the event, we felt, each man’s true nature revealed itself in sharp relief.
在我和一个同事一起观测这个活动时,我们注意到谁是主导者,谁试图领导大家但是被断然拒绝,每个士兵对集体努力的结果付出多少。我们观察到了哪些人是顽固的,哪些是顺从的,哪些是傲慢的,哪些是有耐心的,哪些是脾气暴躁的,哪些是有持续性的或是半途而废的。虽然团队中会出现龃龉:有人因为自己的想法被否定,而不再非常努力。并且,我们看到面对危机的反应:哪些人会斥责造成团队失败的同伴,哪些人会在不得不从新开始时挺身而出,带领已经疲惫的团队。我们认为,该事件的压力下,每个人的真实本性都清晰地显露了出来。
After watching the candidates go through several such tests, we had to summarize our impressions of the soldiers’ leadership abilities with a grade and determine who would be eligible for officer training. We spent some time discussing each case and reviewing our impressions. The task was not difficult, because we had already seen each of these soldiers’ leadership skills. Some of the men looked like strong leaders, others seemed like wimps or arrogant fools, others mediocre but not hopeless. Quite a few appeared to be so weak that we ruled them out as officer candidates. When our multiple observations of each candidate converged on a coherent picture, we were completely confident in our evaluations and believed that what we saw pointed directly to the future. The soldier who took over when the group was in trouble and led the team over the wall was a leader at that moment. The obvious best guess about how he would do in training, or in combat, was that he would be as effective as he had been at the wall. Any other prediction seemed inconsistent with what we saw.
在候选人经过几个这样的测试之后,我们用等级来对每个士兵的领导能力进行总结,并决定谁有资格进行领事官训练。我们花时间讨论每个案子,回顾我们的印象。这个任务并不难,因为我们已经看到这些士兵的领导能力。在他们中,一些人看起来像是强有力的领导者,一些人则像懦夫或自大的傻瓜,一些人则平庸却不绝望。相当多的人表现的很懦弱,我们在选候补军官时将他们排除在外。当我们将每名候选人集中在一个连贯的画面上进行多重观察时,我们完全信任我们的评估结果,并且确信我们所观察到的对未来有着直接地预示作用。当团队遇到困难的时刻,接管并带领团队越过墙的那个士兵就是一个领导者。对他在训练或战斗中将会如何去做的最佳猜测,明显是他会像在越墙时一样有效的进行行动。而任何其他的预测似乎与我们所看到的不一致。
Because our impressions of how well each soldier performed were generally coherent and clear, our formal predictions were just as definite. We rarely experienced doubt or conflicting impressions. We were quite willing to declare: “This one will never make it,” “That fellow is rather mediocre, but should do O.K.” or “He will be a star.” We felt no need to question our forecasts, moderate them or equivocate. If challenged, however, we were fully prepared to admit, “But of course anything could happen.”
因为普遍来说我们对每个士兵表现优劣的印象都是很一致很明确的,我们对他们的正式预测也是同样清晰明确的。我们很少会有疑问或者互相矛盾的印象,我们都很愿意断言: "这个士兵永远达不到我们的要求," "那位仁兄太平庸了,但应该还是可以的." 或者"他注定成为明星." 我们觉得没有必要对我们的预测产生疑问,进行修正或者含糊其辞。但如果我们的预测被人疑问挑战了,我们也都愿意承认,"但是当然这事谁也说不准."
We were willing to make that admission because, as it turned out, despite our certainty about the potential of individual candidates, our forecasts were largely useless. The evidence was overwhelming. Every few months we had a feedback session in which we could compare our evaluations of future cadets with the judgments of their commanders at the officer-training school. The story was always the same: our ability to predict performance at the school was negligible. Our forecasts were better than blind guesses, but not by much.
我们愿意这样承认是因为,往往尽管我们对每个候选人的潜力很确定,我们的预测很大程度上是完全没用的。证据是压倒性的。每隔几个月我们都会有一个回馈环节, 这时我们可以将我们对这些未来的士官的评估和军官训练学校的指挥官的判断进行对比。结局总是一成不变的:我们预测这些士官在学校表现的能力几乎是可以忽略的。我们的预测比蒙着眼睛瞎懵强些,但是也不会强到哪里去。
We were downcast for a while after receiving the discouraging news. But this was the army. Useful or not, there was a routine to be followed, and there were orders to be obeyed. Another batch of candidates would arrive the next day. We took them to the obstacle field, we faced them with the wall, they lifted the log and within a few minutes we saw their true natures revealed, as clearly as ever. The dismal truth about the quality of our predictions had no effect whatsoever on how we evaluated new candidates and very little effect on the confidence we had in our judgments and predictions.
在得知这一消息之后我们着实沮丧了一段时间,但在军队里么,不管有效还是无效,还是要遵守传统和规矩的。第二天来了新的一批候选人。我们带他们到障碍测试的场地,仍然让他们面对着那堵墙,举起了木头,而且和原来一样,我们很快就看到了他们的真实性格。那个令人沮丧的事实并没有影响到我们对新候选人的评判,同样也没有影响到我们对自己判断和预测的信心。
I thought that what was happening to us was remarkable. The statistical evidence of our failure should have shaken our confidence in our judgments of particular candidates, but it did not. It should also have caused us to moderate our predictions, but it did not. We knew as a general fact that our predictions were little better than random guesses, but we continued to feel and act as if each particular prediction was valid. I was reminded of visual illusions, which remain compelling even when you know that what you see is false. I was so struck by the analogy that I coined a term for our experience: the illusion of validity.
我想发生在我们身上的变化是值得注意的。在我们对特定的候选人的判断中,我们失败的统计学证据本来应该挫伤我们的自信,但是实际上没有。虽然我们知道这个简单的道理:我们的预测基本上比胡乱的猜想好不了多少,但是我们还是把每一个特定的预测都假设成是有效的,并继续去感知和测试那些候选人。这让我想起了视觉幻象,它会使你在知道自己所见的是假象的情况下依然强迫你去观察。这种类似的经历使我深受打击,以至于我杜撰了一个关于这次经历的术语:有效性幻象。
I had discovered my first cognitive fallacy.
我发现了我的第一个认知谬误。
Decades later, I can see many of the central themes of my thinking about judgment in that old experience. One of these themes is that people who face a difficult question often answer an easier one instead, without realizing it. We were required to predict a soldier’s performance in officer training and in combat, but we did so by evaluating his behavior over one hour in an artificial situation. This was a perfect instance of a general rule that I call WYSIATI, “What you see is all there is.” We had made up a story from the little we knew but had no way to allow for what we did not know about the individual’s future, which was almost everything that would actually matter. When you know as little as we did, you should not make extreme predictions like “He will be a star.” The stars we saw on the obstacle field were most likely accidental flickers, in which a coincidence of random events — like who was near the wall — largely determined who became a leader. Other events — some of them also random — would determine later success in training and combat.
You may be surprised by our failure: it is natural to expect the same leadership ability to manifest itself in various situations. But the exaggerated expectation of consistency is a common error. We are prone to think that the world is more regular and predictable than it really is, because our memory automatically and continuously maintains a story about what is going on, and because the rules of memory tend to make that story as coherent as possible and to suppress alternatives. Fast thinking is not prone to doubt.
几十年后,我能理解许多以我的那种旧经验作出判断的见解的中心主题。主题之一是,当面对一个困难的问题的时候,人们经常在无意识的情况下回答一个更简单的来代替。我们被要求预测士兵在军官培训中和在战斗中的表现,但我们的预测仅通过评价他在一小时里在人工场景下的表现。这是个普适规则的最好实例,我把它叫作“WYSIATI”,(What you see is all there is)一叶障目。我们从自己所知的冰山一角里编出个故事,却一点也不考虑到我们不确定的个体的未来,那才几乎是真正最重要的全部。当你的了解和我们一样少时,你不应该作出像“他会是个明星”这样极端的预测。那些我们看到的在障碍物场地上的明星很可能只是偶然闪烁,随机事件里的一个巧合,就像谁离墙近谁就成了领导者——很大程度上决定了谁是领导者。其它一些同样随机的事件,会决定后来在军官培训和战斗中的胜出。
你可能惊讶于我们的失败:期待相同的领导力在各种情况下,这很自然。但是过分的一致性(一成不变的)预期是个常见错误。我们更倾向于认为这个世界比她实质上的更规律和可预期,因为我们的记忆会无意识并连续不断地维持一个正在发生的故事,而且记忆的规则趋向于使故事尽可能连贯一致来抑制(故事的)其他可能。快速思考不容易产生怀疑。
The confidence we experience as we make a judgment is not a reasoned evaluation of the probability that it is right. Confidence is a feeling, one determined mostly by the coherence of the story and by the ease with which it comes to mind, even when the evidence for the story is sparse and unreliable. The bias toward coherence favors overconfidence. An individual who expresses high confidence probably has a good story, which may or may not be true.
我们做决定时候体验到的自信,并不是一个基于概率的有理有据的评价。自信是一个赶脚(译者:“赶脚”卖萌挺好的啊)(另一译者:好吧,我也改回赶脚了。。我太不会卖萌了!),主要被叙述故事的通顺和想到这故事的从容而决定,即使对这故事正确性的证据是又少又不可靠。对通顺的偏好容易引发过度自信。一个非常自信的人心里大概有一个(可能真也可能假的)好故事。
I coined the term “illusion of validity” because the confidence we had in judgments about individual soldiers was not affected by a statistical fact we knew to be true — that our predictions were unrelated to the truth. This is not an isolated observation. When a compelling impression of a particular event clashes with general knowledge, the impression commonly prevails. And this goes for you, too. The confidence you will experience in your future judgments will not be diminished by what you just read, even if you believe every word.
我发明了“illusion of validity”这个术语是因为我们对于士兵潜力判断的自信心,并没有被我们明知是真相的统计学事实影响到 --- 我们的预测和真相是毫无联系的。这不是一个孤立的观察结果。当对某个特定事件的强力印象与常识发生碰撞,那种强力印象通常会获胜。对正在读这篇文章的您来说也是如此。你未来下判断时的自信心[强力印象]并不会被你刚刚读到的内容[已成为你"常识"的一部分]而削弱,虽然你相信你读到的每个字。
I first visited a Wall Street firm in 1984. I was there with my longtime collaborator Amos Tversky, who died in 1996, and our friend Richard Thaler, now a guru of behavioral economics. Our host, a senior investment manager, had invited us to discuss the role of judgment biases in investing. I knew so little about finance at the time that I had no idea what to ask him, but I remember one exchange. “When you sell a stock,” I asked him, “who buys it?” He answered with a wave in the vague direction of the window, indicating that he expected the buyer to be someone else very much like him. That was odd: because most buyers and sellers know that they have the same information as one another, what made one person buy and the other sell? Buyers think the price is too low and likely to rise; sellers think the price is high and likely to drop. The puzzle is why buyers and sellers alike think that the current price is wrong.
1984年我第一次拜访了一家华尔街公司。我是和我的长期合作者Amos Tversky一起去的,他在1996年去世了,还有我们的朋友Richard Thaler,现在是行为经济学专家。我们的主持,一个高级投资经理人,邀请我们来讨论判断偏差在投资中的角色。那时候我对金融知之甚少完全不知道问他什么,但是我记得其中一个交流。”在你卖一个股票的时候” 我问他,”买家是谁?” 他朝着大概窗户的方向挥了挥手并回答,他期望买家是和他自己非常相似的人。这很奇怪:因为大多数卖家和买家都知道他们拥有相同的信息,是什么使其中一人买另一人卖呢?买家认为价格太低有可能会升值;卖家爱认为价格太高有可能会下跌。这个难题就是为什么买家和买家在市价不合理这件事上会所见略同。
Most people in the investment business have read Burton Malkiel’s wonderful book “A Random Walk Down Wall Street.” Malkiel’s central idea is that a stock’s price incorporates all the available knowledge about the value of the company and the best predictions about the future of the stock. If some people believe that the price of a stock will be higher tomorrow, they will buy more of it today. This, in turn, will cause its price to rise. If all assets in a market are correctly priced, no one can expect either to gain or to lose by trading.
大多数做投资业务的人都读过Burton Malkiel’s的著作《漫步华尔街》。 Malkiel的中心思想是,一只股票的价格体现在发行公司的价值以及对该股票未来的最好预期相关的所有可知消息里。如果一部分人相信股票明天会升值,他们今天会更多地买入。这相应的就会造成股价地上涨。如果市场里的所有资产都被正确地估价,就没有人能预期交易会是盈还是亏了。
We now know, however, that the theory is not quite right. Many individual investors lose consistently by trading, an achievement that a dart-throwing chimp could not match. The first demonstration of this startling conclusion was put forward by Terry Odean, a former student of mine who is now a finance professor at the University of California, Berkeley.
然而,我们现在知道这个理论并不正确。许多个人投资者在交易中始终赔钱,而这个结果还不如黑猩猩扔飞镖的成绩。对于这个令人吃惊的结论的第一个证明由我以前的学生,现在在加州大学伯克利分校任教的金融学教授Terry Odean提出。
Odean analyzed the trading records of 10,000 brokerage accounts of individual investors over a seven-year period, allowing him to identify all instances in which an investor sold one stock and soon afterward bought another stock. By these actions the investor revealed that he (most of the investors were men) had a definite idea about the future of two stocks: he expected the stock that he bought to do better than the one he sold.
Odean教授分析了10000名个人投资者的证券账户七年间的交易记录,这使得他可以找出一个投资者在卖掉一只股票后马上买入另一只股票的所有事例。通过这些行为,投资者显示出他(大多数投资者是男性)对于两只股票的未来有确定的看法:他预计他买的那只股票会比他卖掉的那只股票在未来表现的更好。
To determine whether those appraisals were well founded, Odean compared the returns of the two stocks over the following year. The results were unequivocally bad. On average, the shares investors sold did better than those they bought, by a very substantial margin: 3.3 percentage points per year, in addition to the significant costs of executing the trades. Some individuals did much better, others did much worse, but the large majority of individual investors would have done better by taking a nap rather than by acting on their ideas. In a paper titled “Trading Is Hazardous to Your Wealth,” Odean and his colleague Brad Barber showed that, on average, the most active traders had the poorest results, while those who traded the least earned the highest returns. In another paper, “Boys Will Be Boys,” they reported that men act on their useless ideas significantly more often than women do, and that as a result women achieve better investment results than men.
为了确定这些估价是否正确,Odean教授比较了两只股票在以后的年份里的回报。结果十分糟糕。平均下来,投资者卖掉的那些股份表现上大幅优于他们买的那些股份,每年高达3.3%,与此同时还没有算上交易股票所产生的巨大费用。一些人的确做得业绩更好,一些人做得更差,但是绝大多数投资者都可以做得更好,如果他们只是打个盹而不是根据他们的想法进行股票交易。在一篇标题为“交易行为使你的财富面临危险”的论文中,Odean教授和他的同事Brad Barber提出,平均下来。最活跃的交易者有着最差的结果,然而那些进行了最少交易的人得到了最高的回报。在另一篇论文“男孩将会成为男人”中,他们说,男人比女人更经常地按照他们毫无用处的想法行事,所以,女人比男人有更好的投资回报。
Of course, there is always someone on the other side of a transaction; in general, it’s a financial institution or professional investor, ready to take advantage of the mistakes that individual traders make. Further research by Barber and Odean has shed light on these mistakes. Individual investors like to lock in their gains; they sell “winners,” stocks whose prices have gone up, and they hang on to their losers. Unfortunately for them, in the short run going forward recent winners tend to do better than recent losers, so individuals sell the wrong stocks. They also buy the wrong stocks. Individual investors predictably flock to stocks in companies that are in the news. Professional investors are more selective in responding to news. These findings provide some justification for the label of “smart money” that finance professionals apply to themselves.
当然,总有人处在一个交易行为的另一端;大体上来说,总是一个金融机构或是一名专业投资者准备利用那些个人投资者犯下的错误。Barber教授和Odean教授更进一步的研究聚焦于于个人投资者犯下的错误。个人投资者喜欢锁定他们的收益:他们卖出那些股价升高的“赢家”股票,并且坚守那些“失败者”股票。对于他们来说,很不幸的是,在短期上,近期的“赢家”往往比近期的“失败者”表现得更好,所以个人投资者卖错了股票。他们也买错股票。个人投资者可预见地涌向那些被报导公司的股票。专业投资者往往是有选择性的对于新闻做出回应。这些发现为金融专家们给自己贴的标签“聪明钱”提供了证明。
Although professionals are able to extract a considerable amount of wealth from amateurs, few stock pickers, if any, have the skill needed to beat the market consistently, year after year. The diagnostic for the existence of any skill is the consistency of individual differences in achievement. The logic is simple: if individual differences in any one year are due entirely to luck, the ranking of investors and funds will vary erratically and the year-to-year correlation will be zero. Where there is skill, however, the rankings will be more stable. The persistence of individual differences is the measure by which we confirm the existence of skill among golfers, orthodontists or speedy toll collectors on the turnpike.
尽管专家们可以从业余投资者那里获得很大一笔财富,很少有人(如果有的话)有能力持续地、一年又一年地战胜市场。任何技术,其存在的特征是个体成就差异的稳定性。背后的逻辑很简单:如果个体成就上的差异在某一年中完全是由于运气造成的,那么投资者和基金的排名每年都会不规律地改变,而且每年排名的相关性将会是零。但是,如果拥有技术,排名就会更加稳定。个体成就上差异的持续正是我们肯定高尔夫球手,整牙医师以及在收费高速路口快速收费的收费员拥有技术的方法。(这段觉得好别扭。不知道该怎么改。。大家帮帮忙吧)
Mutual funds are run by highly experienced and hard-working professionals who buy and sell stocks to achieve the best possible results for their clients. Nevertheless, the evidence from more than 50 years of research is conclusive: for a large majority of fund managers, the selection of stocks is more like rolling dice than like playing poker. At least two out of every three mutual funds underperform the overall market in any given year.
共同基金通常是由非常有经验的并且十分勤勉的专业人士来运营的,他们买卖股票以为客户带来最好的结果。然而,从超过50年的研究中得到的证据得出一个非常确定的结论:对于大多数基金经理来说,选择股票与其说是打扑克,更像是掷色子。至少三分之二的共同基金都在任何一个特定年份中跑输整体市场。
More important, the year-to-year correlation among the outcomes of mutual funds is very small, barely different from zero. The funds that were successful in any given year were mostly lucky; they had a good roll of the dice. There is general agreement among researchers that this is true for nearly all stock pickers, whether they know it or not — and most do not. The subjective experience of traders is that they are making sensible, educated guesses in a situation of great uncertainty. In highly efficient markets, however, educated guesses are not more accurate than blind guesses.
更重要的是,共同基金每年的投资结果相关性非常小,接近于零。在特定一年中成功的基金原因大多是运气好;他们恰巧赶上色子滚得好(滚得好。。。不对劲)。研究者们关于挑选股票的人达成了一个共识,无论他们中大多数是否知道——大多数人不知道。交易者的主观经验是他们在一个具有高度不确定性的环境中进行着明智的(sensible在这里应该怎么翻译?感觉明智不太对。)、有根据的猜测。然而,在一个高效的市场中,有根据的猜测并不比瞎蒙更准确。
Some years after my introduction to the world of finance, I had an unusual opportunity to examine the illusion of skill up close. I was invited to speak to a group of investment advisers in a firm that provided financial advice and other services to very wealthy clients. I asked for some data to prepare my presentation and was granted a small treasure: a spreadsheet summarizing the investment outcomes of some 25 anonymous wealth advisers, for eight consecutive years. The advisers’ scores for each year were the main determinant of their year-end bonuses. It was a simple matter to rank the advisers by their performance and to answer a question: Did the same advisers consistently achieve better returns for their clients year after year? Did some advisers consistently display more skill than others?
在我接触了金融世界一些年后,我获得一个可以近距离研究对于技术的错觉的机会。我受邀去一个为非常富有的客户提供理财咨询和其他服务的公司,向一群投资顾问做报告。我要来了一些数据用来准备我的报告,于此同时得到了一小笔财富:一个总结了25位匿名的投资顾问连续八年的投资业绩的电子表格。投资顾问们每年的业绩是他们年终奖金的主要决定因素。把投资顾问按他们的业绩进行排名并回答一个问题变成了很简单的事情。同一名顾问是否可以连续地每年都为客户带去更高的回报?一些顾问是不是可以持续地相较于其他人展现出更多技术?
To find the answer, I computed the correlations between the rankings of advisers in different years, comparing Year 1 with Year 2, Year 1 with Year 3 and so on up through Year 7 with Year 8. That yielded 28 correlations, one for each pair of years. While I was prepared to find little year-to-year consistency, I was still surprised to find that the average of the 28 correlations was .01. In other words, zero. The stability that would indicate differences in skill was not to be found. The results resembled what you would expect from a dice-rolling contest, not a game of skill.
为了寻找答案,我计算了不同年份中顾问的排名的相关性,把第一年的排名与第二年的排名对比,把第一年的排名与第三年的排名对比,直到把第七年的排名与第八年的排名进行对比。就这样,产生了28个相关性数据,每一个对应一组年份。尽管我对于发现非常小的年与年之间的相关性有所预期,我仍然很惊讶地发现28组数据的相关性平均数只有0.01。换句话说,就是零。可以用来表示技术差异的稳定性并没有被发现。这个结果就跟你能在掷色子比赛中期待的一样,这压根不是一个有关技术的比赛。
No one in the firm seemed to be aware of the nature of the game that its stock pickers were playing. The advisers themselves felt they were competent professionals performing a task that was difficult but not impossible, and their superiors agreed. On the evening before the seminar, Richard Thaler and I had dinner with some of the top executives of the firm, the people who decide on the size of bonuses. We asked them to guess the year-to-year correlation in the rankings of individual advisers. They thought they knew what was coming and smiled as they said, “not very high” or “performance certainly fluctuates.” It quickly became clear, however, that no one expected the average correlation to be zero.
公司里似乎没有人意识到他们的股票挑选者所玩的游戏的本质。那些顾问他们自己认为他们是一群有能力的专家进行着一项十分困难但是并不是完全不可能的任务,他们的上级也这么认为。在报告会的前一天晚上,Richard Thaler和我一起与公司里的高级主管人员共进了晚餐,正是这些高级主管人员决定奖金的多少。我们请他们猜投资顾问的排名在历年的相关性。他们认为他们知道将要发生什么,笑着说:“不是很高”或者“表现肯定会有波动”。然而,事实很快变得明朗起来,根本没有人预料到平均相关性会是零。
What we told the directors of the firm was that, at least when it came to building portfolios, the firm was rewarding luck as if it were skill. This should have been shocking news to them, but it was not. There was no sign that they disbelieved us. How could they? After all, we had analyzed their own results, and they were certainly sophisticated enough to appreciate their implications, which we politely refrained from spelling out. We all went on calmly with our dinner, and I am quite sure that both our findings and their implications were quickly swept under the rug and that life in the firm went on just as before. The illusion of skill is not only an individual aberration; it is deeply ingrained in the culture of the industry. Facts that challenge such basic assumptions — and thereby threaten people’s livelihood and self-esteem — are simply not absorbed. The mind does not digest them. This is particularly true of statistical studies of performance, which provide general facts that people will ignore if they conflict with their personal experience.
我们告诉公司的主管们的是,至少在建立投资组合时,公司是在把运气当做技术来奖励。这本他们来说本应是令人震惊的消息,但事实上却不是。并没有任何迹象表明他们不相信我们。他们为什么会这样?毕竟,我们分析的是他们自己的业绩,他们也老练到足以领会对他们的暗示,鉴于礼貌的原因,我们克制住自己,并没有说出来。(这句appreciate their implications指什么?)我们继续平静地进行着我们的晚餐,我十分确定我们的发现和他们的暗示很快地就被回避了,在公司里的生活继续像以前一样进行着。对于技术的错觉不仅仅是个人的失常,它是根深蒂固在行业的文化中的。那些挑战最基本的假设,进而威胁到人们的生计和自尊的事实,轻易地被忽略了。大脑并不处理它们。这在关于表现的统计学研究中尤为突出,这些研究为人们提供一些事实,如果事实与人们自身经验相冲突,人们就会忽略它们。
The next morning, we reported the findings to the advisers, and their response was equally bland. Their personal experience of exercising careful professional judgment on complex problems was far more compelling to them than an obscure statistical result. When we were done, one executive I dined with the previous evening drove me to the airport. He told me, with a trace of defensiveness, “I have done very well for the firm, and no one can take that away from me.” I smiled and said nothing. But I thought, privately: Well, I took it away from you this morning. If your success was due mostly to chance, how much credit are you entitled to take for it?
第二天早晨,我们向顾问们汇报了我们的发现,而他们同样反应的平淡无奇. 在复杂的问题上,他们的私人经验是小心的给予专业意见,对他们来说这个做法要比相信晦涩的统计数据结果重要的多。当我们结束时,一个前一晚和我一起吃晚餐的主管开车送我去机场. 他带着一丝抵触的语气同我说,"一直以来我对公司尽心尽力,没有人可以否定我的工作。" 我笑了笑没有说任何话。但是私下里我想:真可惜,我今天早晨已经否定了你的工作。如果你工作的成功大部分是取决于运气,你有多少资格向公司邀功呢?
We often interact with professionals who exercise their judgment with evident confidence, sometimes priding themselves on the power of their intuition. In a world rife with illusions of validity and skill, can we trust them? How do we distinguish the justified confidence of experts from the sincere overconfidence of professionals who do not know they are out of their depth? We can believe an expert who admits uncertainty (but cannot take expressions of high confidence at face value)Help!!. As I first learned on the obstacle field, people come up with coherent stories and confident predictions even when they know little or nothing. Overconfidence arises because people are often blind to their own blindness.
我们经常与专家们互相影响,他们带着显而易见的自信运用自己的判断,有时对自己直觉的力量引以为傲。在这个充斥着有效度和技巧幻觉的世界里,我们能信任他们吗?要怎么才能从那些明明力所不及、真挚但过度自信的专家里,分辨出那些恰当自信的专家?我们能相信一个承认不确定性的专家,但不能以高度自信表情的表面现象取人。我第一次在障碍物场地上学习到,即使所知甚少,人们还是会想出连贯的故事和作出自信的预测。自负的出现是因为人们无知于自己的无知
True intuitive expertise is learned from prolonged experience with good feedback on mistakes. You are probably an expert in guessing your spouse’s mood from one word on the telephone; chess players find a strong move in a single glance at a complex position; and true legends of instant diagnoses are common among physicians. To know whether you can trust a particular intuitive judgment, there are two questions you should ask: Is the environment in which the judgment is made sufficiently regular to enable predictions from the available evidence? The answer is yes for diagnosticians, no for stock pickers. Do the professionals have an adequate opportunity to learn the cues and the regularities? The answer here depends on the professionals’ experience and on the quality and speed with which they discover their mistakes. Anesthesiologists have a better chance to develop intuitions than radiologists do. Many of the professionals we encounter easily pass both tests, and their off-the-cuff judgments deserve to be taken seriously. In general, however, you should not take assertive and confident people at their own evaluation unless you have independent reason to believe that they know what they are talking about. Unfortunately, this advice is difficult to follow: overconfident professionals sincerely believe they have expertise, act as experts and look like experts. You will have to struggle to remind yourself that they may be in the grip of an illusion.
真实直观的专业知识的习得依赖于从错误中获得好的反馈的长期经验。从电话交谈的一句话里猜测出自己配偶的情绪,在那方面你很可能是个专家;在复杂的棋盘上的一个眼神,国际象棋选手就能发现一步极好的棋;医师真实的传说般瞬间作出诊断也很正常。要知道自己是否能相信一个特定的直觉判断,你要问两个问题:1.做出判断的环境是否足够规律,使从现有证据里作出的预言成为可能?对于诊断医生来说答案是肯定的,对于拣股者是否定的。2.专家是否有充分的机会获悉线索和规律?回答取决于专家的经验,和他们发觉自己错误的质量和速度。麻醉医师比放射科医师有更好的机会开发自己的直觉。我们遇到的许多专家轻松地通过了这两个问题的测试,他们的即兴判断就值得被严肃看待。但一般来说,你不应采信来自独断自信的人他们自己的评估,除非你有能独立判断的理由来相信,他们熟悉他们所谈论的。不幸的是,这条忠告很难被遵从。自负的专家由衷地相信自己有最专业的知识,做起来或者看上去都像个行家。你必须努力提醒自己,他们可能陷入了自己错误的信仰里。
Daniel Kahneman is emeritus professor of psychology and of public affairs at Princeton University and a winner of the 2002 Nobel Prize in Economics. This article is adapted from his book “Thinking, Fast and Slow,” out this month from Farrar, Straus & Giroux.
Editor: Dean Robinson
Daniel Kahneman是普林斯顿大学心理学和公共事务学的退休教授,他也是2002年诺贝尔经济学奖的获奖者。这篇文章是从他的著作《思考,快与慢》(http://book.douban.com/subject/10785583/) 改编而来的,这本书将于本月由Farrar, Straus & Giroux出版。
编辑:Dean Robinson
建议中文和英文分开,一段英文一段中文,看起来很累的,呵呵
即便玩筛子,基金们玩得也还是很HIGH,连年新发导致找个相熟的老基金都困难。。。
万一知道自己不知道,那种不确定感该怎么办?
好长,读完了没看懂==
合并在一起不是为了让你同时看的(what's the point seriously),是为了让你在看中文翻译有不明白的时候可以参照英文。
试翻译:虽然专业投资者能从业余投资者那儿获取相当可观的财富,(但)很少选股人(如果有的话),拥有年复一年持续战胜市场的技能。判断一种技能是否存在的标准是个体成绩差距的持续性。背后的逻辑是简单的: 如果在某一年个体成绩的差距完全归功于运气,那么投资者和基金的排名会不规律地变动,并且每年的排名相关性会为零。如果存在技能因素,则排名会更稳定。这种个体差距的持续性是我们用于衡量高尔夫球手、牙科医师以及高速公路收费员是否存在技能的标准。
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