Thread by @ReformedTrader

1/ The Undoing Project (Michael Lewis)

"What were people’s minds doing that led to the misjudgments that could be exploited for profit by those who ignored experts and relied on data?

"How does a psychologist win a Nobel Prize in economics?" (p. 20)

amazon.com/Undoing-Projec…

2/ "A big part of a consultant’s job was to feign total certainty about uncertain things.

"In a job interview with McKinsey, they told Morey that he was not certain enough in his opinions. ‘We’re billing clients five hundred grand a year, so you have to be sure.’

3/ "The firm was forever asking him to exhibit confidence when, in his view, confidence was a sign of fraudulence. They’d asked him to forecast oil for clients, for instance.

"What people said when they “predicted” was phony: pretending to know rather than actually knowing.

4/ "There were many interesting questions to which the only honest answer was, “It’s impossible to know for sure.” “What will the price of oil be in ten years?” was such a question. That didn’t mean you gave up; you just couched the answer in probabilistic terms." (p. 28)

5/ "The mind was bad at seeing things it did not expect (and too eager to see what it expected). “Confirmation bias is insidious because you don’t even realize it is happening.”

"A scout would settle on an opinion about a player and then arrange evidence to support that opinion.

6/ “The classic thing, and this happens all the time: If you don’t like a prospect, you say he has no position. If you like him, you say he’s multipositional. If you like a player, you compare his body to someone good. If you don’t like him, you compare him to someone who sucks.”

7/ "The mind’s best trick was to create a feeling of certainty about inherently uncertain things. Over and again in the draft, the minds of basketball experts formed crystal-clear pictures which later proved a mirage.

8/ "When Jeremy Lin’s coach finally put him in the game—because everyone else was injured—and allowed him to light up Madison Square Garden, the Knicks were preparing to release Lin. He had already decided that if he was released, he’d simply quit basketball altogether.

9/ "That’s how bad the problem was: a very good NBA player would never have been given a serious chance to play in the NBA simply because the minds of experts had concluded he did not belong. How many other Jeremy Lins were out there?" (p. 42)

10/ ”Every year, it is totally pointless. I’m starting to think psychologists are complete charlatans.” The last one had used Myers-Briggs to try to predict behavior—and then tried to persuade Morey, after the fact, that he had warded off all manner of unseen problems.

11/ "The way he’d gone on reminded Daryl Morey of a joke. “The guy walks around with a banana in his ear. And people are like, ‘Why do you have a banana in your ear?’ He says, ‘To keep the alligators away! There are no alligators! See?’ ” (p. 47)

12/ "Why had so much conventional wisdom been BS, not just in sports, but across society? Why had so many industries been ripe for disruption?

"It was curious that a putatively competitive market for highly paid athletes could be so inefficient in the first place.

13/ "It was strange that when people bothered to measure what happened on court, they'd measured the wrong things so happily for so long. It was bizarre that it was even possible for a total outsider to walk in with an entirely new approach to valuing basketball players." (p. 50)

14/ "A light appeared brighter when it emerged from total darkness; the color gray looked green when it was surrounded by violet and yellow if surrounded by blue; if you said to a person, “Don’t step on that banana eel!,” he’d be sure that you had said not “eel” but “peel.”

15/ "The Gestalists showed that there was no obvious relationship between external stimulus and sensation, as the mind intervened in many curious ways.

"How does the brain create meaning? How does it turn the fragments collected by the senses into a coherent picture of reality?

16/ "Why does that picture seem to be imposed by the mind upon the world around it, rather than by the world upon the mind? How does a person turn the shards of memory into a coherent life story? Why does a person’s understanding of what he sees change with context?" (p. 71)

17/ "When Danny tested his predictions against outcomes—how candidates had actually performed in officer training—his predictions were worthless.

"Yet, because it was the army and he had a job to do, he kept on making them—and he noted that he still felt confident about them.

18/ "Even after you prove to people, with a ruler, that the lines are identical, the illusion persists. If perception had the power to overwhelm reality in such a simple case, how much power might it have in a more complicated one?" (p. 78)

More on this:

https://twitter.com/ReformedTrader/status/1302343976175902720

19/ On the halo effect: “A halo of general merit is extended to influence the rating for the special ability, or vice versa... even a very capable employer is unable to view an individual's separate qualities and assign a magnitude to each in independence of the others.” (p. 78)

20/ "Psychoanalysts's predictions of what would become of their neurotic patients fared poorly compared to simple algorithms.

"This angered psychoanalysts, who believed their clinical judgments had great value.

"If putative experts could be misled, who would not be?" (p. 80)

21/ "Economists assumed people were “rational” and knew they wanted. Given some array of choices, they could order them logically based on their tastes.

"If they said they preferred coffee to tea, and tea to hot chocolate, they should logically prefer coffee to hot chocolate.

22/ "In academic jargon, they were “transitive.”

"But more than a quarter of students had revealed themselves as irrational from this point of view. They would rather marry Jim than Bill, and Bill than Harry—but then also said that they would rather marry Harry than Jim.

23/ "May suggested the beginning of an explanation: Because Jim and Bill and Harry each had relative strengths and weaknesses, they were hard to compare. “Comparison of alternatives in which one is superior in every respect makes for a simple but rather trivial theory.” " (p.104)

24/ "Israeli Air Force instructors believed that criticism was more useful than praise. The pilot who was praised (criticized) performed worse (better) the next time out.

"Danny explained what was actually going on: the pilots were simply regressing to the mean.

25/ "They’d have tended to perform better (or worse) even if the teacher had said nothing at all.

"Statistics wasn’t just boring numbers; it contained ideas that allowed you to glimpse deep truths about human life." (p. 126)

26/ "None of the psychoanalysts—world experts who had spent a month studying the woman’s mental state—had worried she might kill herself. None of their reports so much as hinted at the risk of suicide.

" “Now they agreed, 'How could we have missed it? The signs were all there!'

27/ "It made so much sense to them after the fact. And so little sense before the fact.”

"This was instructive, not about the troubled patients, but about the psychoanalysts—or anyone else who was in a position to revise his forecast after the fact." (p. 132)

28/ "People become attached to a theory and fit the evidence to theory rather than the theory to the evidence. They cease to see what’s right under their noses.

"Idiocies were accepted as truths because they were embedded in a theory to which scientists had yoked their careers.

29/ “For decades, psychologists thought behavior was explained by learning, and they studied learning by looking at rats in mazes. The people who thought it was BS were not smarter than the brilliant people who dedicated their careers to what we now see as rubbish.” (p. 149)

30/ "Even statisticians tended to leap to conclusions from small amounts of evidence. They did this, Amos and Danny argued, because they believed—even if unacknowledged—that any given sample of a large population was more representative of that population than it actually was.

31/ "People believed that if a flipped coin landed on heads a few times in a row it was more likely, next time, to land on tails—as if the coin itself could even things out.

"People had so much faith in small samples that they tended to rationalize whatever they found in them.

32/ "Statistics was the way you should think about probabilistic situations, but statistics was not the way people did it. The test subjects were all sophisticated in statistics—and even they got it wrong!" (p. 163)

33/ "A simple model was extremely good at predicting doctors’ diagnoses. That did not mean that their thinking was simple, only that it could be captured by a the model.

"More surprisingly, the doctors’ diagnoses were all over the map: The experts didn’t agree with each other.

34/ "When presented with duplicates of the same ulcer, every doctor contradicted himself and rendered more than one diagnosis: doctors could not even agree with themselves.

“Diagnostic agreement in clinical medicine may not be much greater than for clinical psychology.”

35/ "The researchers then repeated the experiment with clinical psychologists and psychiatrists, who gave them the list of factors they considered when deciding whether it was safe to release a patient from a psychiatric hospital. Once again, the experts were all over the map.

36/ "Those with the least training (graduate students) were just as accurate as the fully trained ones (paid pros) in their predictions. Experience appeared to be of little value in judging, say, whether a person was at risk of committing suicide." (p. 172)

37/ "The simple algorithm had outperformed not merely the group of radiologists; it had outperformed even the single best one. You could beat the doctor by replacing him with an equation created by people with no medical knowledge and had simply asked a few questions of doctors.

38/ "It was as if the doctors had a theory of how much weight to assign to any given trait of any given ulcer. The model captured their theory... but in practice, they did not abide by their own ideas. As a result, they were beaten by their own model." (p. 174)

39/ "Londoners in WWII thought that German bombs were targeted: some parts of the city were hit repeatedly while others were not hit at all.

"(Statisticians later showed that the distribution was exactly what you would expect from random bombing.)

40/ "People find it a remarkable coincidence when two students in the same classroom share a birthday, when in fact there is a better than even chance, in any group of twenty-three people, that two of its members will have been born on the same day.

41/ "Our minds' stereotype of “randomness” lacks the clusters and patterns that occur in true random sequences.

"If our minds can be misled by our false stereotype of something as measurable as randomness, how much might they be misled by other, vaguer stereotypes?" (p. 186)

42/ "The more easily people can call some scenario to mind, the more probable they find it to be. Anything especially vivid, or recent, or common—or anything that happened to preoccupy a person—was likely to be disproportionately weighted in that person's judment and decisions.

43/ "Danny and Amos had noticed how unreliably their own minds recalculated odds.

"After they drove past a gruesome car crash, they slowed down. After seeing a movie dramatizing nuclear war, they worried more about nuclear war; indeed, they felt it was more likely to happen.

44/ "The test subjects almost always got it backward: If the list they had listened to had more male names on it, but the women’s names were famous, they thought the list contained more female names, and vice versa.

45/ "If the evidence needed to judge situations accurately was hard to retrieve from memories, and misleading evidence came easily to mind, people made mistakes. “Consequently,” Amos and Danny wrote, “the use of the availability heuristic leads to systematic biases.” " (p. 191)

46/ "People could be anchored with information that was totally irrelevant to the problem they were being asked to solve.

"People who spun a higher number on a wheel tended to guess that a higher percentage of the United Nations consisted of African countries." (p. 192)

47/ "In complicated real-life problems—when trying to decide if Egypt might invade Israel, say, or their husband might leave them for another woman—people constructed scenarios. The stories we make up, rooted in our memories, effectively replace probability judgments.

48/ " “Producing a compelling scenario is likely to constrain future thinking,” wrote Danny and Amos. “There is much evidence showing that, once an uncertain situation has been perceived or interpreted in a particular fashion, it is quite difficult to view it in any other way.”

49/ “Images of the future are shaped by experience of the past. We often decide that an outcome is extremely unlikely or impossible because we are unable to imagine any chain of events that could cause it to occur. The defect, often, is in our imagination.”

50/ “This tendency to consider only relatively simple scenarios affects in situations of conflict. There, one’s own moods and plans are more available to one than those of the opponent. It is not easy to adopt the opponent’s view of the chessboard or of the battlefield.” (p. 194)

51/ "To Amos and Danny, a judgment (“he looks like a good army officer”) implies a prediction (“he will make a good army officer”), just as a prediction implies some judgment—without a judgment, how would you predict?

"A prediction is a judgment that involves uncertainty.

52/ “For predictions and judgments under uncertainty, people do not appear to follow the statistical theory of prediction. Instead, they rely on a limited number of heuristics which sometimes yield reasonable judgments and sometimes lead to severe and systematic error.” (p. 197)

53/ "Base rates were what you would predict if you had no information.

"The test subjects ignored all objective data and went with gut sense.

"If people allowed stereotypes to warp their judgment, what kind of predictions might they make if given totally irrelevant information?

54/ "They told subjects that they had picked a person from a pool of 100 people, 70 of whom were engineers and 30 of whom were lawyers. Then they asked them: What is the likelihood that the selected person is a lawyer? The subjects correctly judged it to be 30%.

55/ "For 70 lawyers and 30 engineers, they said, correctly, that there was a 70% chance the person was a lawyer.

"But if you told them you'd picked a guy named Dick, and read a description—which contained no information whatsoever to help you guess what Dick did for a living...

56/ "...they guessed there was an equal chance that Dick was a lawyer/engineer. ”When worthless specific evidence is given, prior probabilities are ignored.”

"The very factors that caused people to become more confident also led their predictions to be less accurate." (p. 202)

57/ "Within a very short time we come up with an explanation, hypothesis, or interpretation that renders observations understandable, coherent, or natural. The same phenomenon is observed in perception. People are very good at detecting patterns and trends, even in random data.

58/ Amos: "Our ability to assess our interptations' likelihood or to evaluate them critically is grossly inadequate. Once we have adopted a particular hypothesis, we exaggerate the likelihood of that hypothesis and find it very difficult to see things any other way." (p. 206)

59/ "Historians made facts they had observed (neglecting the many facts they could not observe) fit neatly into a confident-sounding story.

Amos: "We find ourselves unable to predict what will happen; yet after the fact we explain what did happen with a great deal of confidence.

60/ "It leads us to believe the world is less uncertain than it actually is.

"If we can explain tomorrow what we cannot predict today, without added information except the outcome, then this outcome must have been determined in advance: we should have been able to predict it."

61/ "Historians imposed false order upon random events, probably without even realizing what they were doing. Amos called it “creeping determinism” and noted one of its many costs: “He who sees the past as surprise-free is bound to have a future full of surprises.” " (p. 207)

62/ Redelmeier: “Brilliant physicians were not immune to fallibility.

“In math, you check your work. In medicine, no. And if we are fallible in algebra, where the answers are clear, how much more fallible must we be in a world where the answers are much less clear?” (p. 223)

63/ ”For arthritis, selective matching leads people to look for changes in the weather when they experience increased pain and pay little attention to the weather when pain is stable. A single day of severe pain and extreme weather might sustain a lifetime of belief.” (p. 232)

64/ "People's memory of pain was different from their experience of it. They remembered moments of maximum pain, and they remembered, especially, how they felt the moment the pain ended. But they didn’t particularly remember the length of the painful experience.

65/ "If you stuck people’s arms in ice buckets for three minutes but warmed the water just a bit for another minute, they remembered the experience more fondly.

"People preferred to endure more total pain so long as the experience ended on a more pleasant note." (p. 234)

66/ "Those given the less unhappy ending remembered less pain and were more likely to return for another colonoscopy.

"People who never imagined that they might prefer more pain could nearly all be fooled into doing so. “Last impressions can be lasting impressions.” " (p. 235)

67/ “We have attempted to teach people to be aware of the pitfalls and fallacies of their own reasoning. We have attempted to teach people at various levels in government, army etc. but achieved only limited success.”

68/ "What was the point of laying out the odds, if the person either didn’t believe the numbers or didn’t want to know them? “The understanding of numbers is so weak that they don’t communicate anything. Everyone feels that those probabilities are not real.” " (p. 250)

69/ "In people’s perceptions of money, as surely as in their perception of light and sound and the weather, what mattered was not the absolute levels but changes. People made choices in terms of gains and losses; they weren’t thinking about absolute levels." (p. 267)

70/ "To get people to prefer a 50-50 chance of winning (losing) $1,000 over a certain gain (loss), you had to lower the certain gain (loss) to $370.

”The happiness involved in receiving a desirable object is smaller than the unhappiness involved in losing that object.” (p. 269)

71/ "People responded to probabilities not just with reason but with emotion. The emotion became stronger as the odds became more remote. If you told them that there was a one-in-a-billion chance that they’d win or lose money, they behaved as if the odds were only one in 10,000.

72/ "They feared a one-in-a-billion chance of loss more than they should and attached more hope to a one-in-a-billion chance of gain than they should. This led them to become risk-seeking for a long-shot gain and risk-avoiding for the extremely remote possibility of loss.

73/ "...why people buy lottery tickets and insurance. “If you think about the possibilities at all, you do so too much. When your daughter is late, it fills your mind even when you know there is very little to fear.” You’d pay more than you should get rid of that worry." (p. 271)

74/ Framing: "Simply by changing the description of a situation, making a gain seem like a loss, you could cause people to flip their attitude toward risk (from risk-avoiding to risk-seeking).

"People did not choose between things. They chose between descriptions of things.

75/ "Economists assumed that you could measure what people wanted from what they chose. But what if what you want changes with context? “It was funny because the point within psychology would have been banal. Of course we are affected by how the decision is presented!” " (p. 278)

76/ "Thaler kept a list of irrational things people do that economists claim that they don’t do:

* the willingness to pay 100x more to avoid a 1/1000 chance of being infected with an disease than they were for the cure after they already had a 1/1000 chance of having it

77/ "* His fellow economists filled up on cashews, which meant they had less appetite for dinner. They tended to be relieved when he removed the cashew nuts so that they didn’t ruin their dinners. “Being better off with fewer choices—that idea was alien to economics.”

78/ "* Why were people slow to sell vacation homes that they would never buy if the same homes were offered to them today?

* Why were NFL teams so reluctant to trade their draft picks when it was obvious that they could often get more than the players were worth in exchange?

79/ "* Why were investors reluctant to sell stocks that had fallen in value, even when they admitted that they would never buy those stocks at their current market prices? (the Endowment Effect)

"There was no end of things people did that economic theory had trouble explaining.

80/ "His fellow economists weren’t interested. ‘We know people make mistakes, but the mistakes are random, and they’ll wash out in the market.’

"Thaler's list did not win him friends in the University of Rochester’s Department of Economics or its business school.

81/ "But if people could be systematically wrong, their mistakes couldn’t be ignored. The irrational behavior of the few would not be offset by the rational behavior of the many.... and so markets could be systematically wrong, too." (p. 284)

82/ Amos: “A theory of vision cannot be faulted for predicting optical illusions. Similarly, a descriptive theory of choice cannot be rejected on the grounds that it predicts ‘irrational behavior’ if the behavior in question is, in fact, observed.” (p. 285)

83/ “What made the theory important and what made it viable were completely different,” said Danny, years later. “Science is a conversation: you have to compete for the right to be heard. And the rules, oddly enough, are that you are tested on formal theory.”

84/ "After they finally sent a draft of their paper to the economics journal Econometrica, Danny was perplexed by the editor’s response. “I was kind of hoping he’d say, ‘Loss aversion is a really cool idea.’ He said, ‘No, I like the math.’ I was sort of shattered.” " (p. 286)

85/ "In a series of famous papers, Hobson had landed body blows on the Freudian idea that dreams arose from unconscious desires: they actually came from a part of the brain that had nothing to do with desire.

86/ "The timing and the length of dreams were regular and predictable, suggesting dreams had less to say about a person’s psychological state than about his nervous system. This suggested that people who paid psychoanalysts to find meaning were wasting their money." (p. 291)

87/ "In the early 1970s, Danny was introduced to the prominent philosopher Max Black and tried to explain his work with Amos. “I’m not interested in the psychology of stupid people,” said Black. But Danny and Amos didn’t think of their work as the psychology of stupid people.

88/ "Their first experiments, dramatizing the weakness of statistical intuition, had been conducted on professional statisticians. For every problem that fooled undergraduates, they could come up with a more complicated version to fool professors. Some professors didn’t like it.

89/ "The first to take it personally were the psychologists whose work it had trumped.

"No matter how often people trained in statistics affirmed the truth of Danny and Amos’s work, people who weren’t would insist that they knew better." (p. 318)

90/ "People with whom Amos interacted were invested in the idea that people were rational. Amos was perplexed by their inability to admit defeat. “Amos wanted to crush the opposition. He wanted to find something to shut people up. Which, of course, you can never do.” (p. 322)

91/ "People were blind to logic when it was embedded in a story. Describe a very sick old man and ask people: Which is more probable, that he will die within a week or within a year? More often than not, they will say, “A week.” The story masks the logic of the situation.

92/ "Which is more likely to happen in the next year, that a thousand Americans will die in a flood, or that an earthquake in California will trigger a massive flood that will drown a thousand Americans? People went with the earthquake.

93/ "The force that led human judgment astray was “representativeness,” the similarity between whatever people were judging and some mental model of that thing. They matched details to their mental models, judging the special case to be more likely than the general one." (p. 325)

94/ "They put it to graduate students with training in logic and statistics. They put it to doctors, in a complicated medical story, in which lay embedded the opportunity to make a fatal error of logic. In overwhelming numbers, doctors made the same mistakes as undergraduates.

95/ "Any prediction could be made to seem more believable, even while becoming less likely, when filled with internally consistent details.

"A lawyer could make a case seem more persuasive, even its truth became less likely, by adding “representative” details to his description.

96/ "People guessed, on average, that a 2,000-word text contained 13.4 seven-letter words ending in -ing and only 4.7 seven-letter words with 'n' in the sixth position. (It was easier to think of words ending in -ing: the availability heuristic in action.)" (p. 328)

97/ "The rules of thumb that the mind used to cope with uncertainty often worked well. But sometimes they didn’t. Why not study them to understand the mind's inner workings? After all, no one complained when you used optical illusions to understand the eye." (p. 334)

98/ " “Prospect Theory” scarcely cited in its first decade, would become, by 2010, the second most cited paper in all economics. “People tried to ignore it: old economists never change their minds.” By 2016, every tenth paper in economics would have a behavioral angle." (p. 342)

99/ "The decisions people made were driven by the way they were presented. People didn’t simply know what they wanted; they took cues from their environment. They constructed their preferences. And they followed paths of least resistance, even when they paid a heavy price for it.

100/ "Millions of U.S. corporate and government employees woke up one day and found they no longer needed to enroll themselves in retirement plans but instead were automatically enrolled. Participation rose by 30%. Such was the power of choice architecture." (p. 343)

101/ " “Amos gave everyone permission to accept human error,” said Redelmeier. That was how Amos made the world a better place, even if it was impossible to prove." (p. 346)

102/ Related reading:

https://twitter.com/ReformedTrader/status/1302337159303540737

103/

https://twitter.com/ReformedTrader/status/1320889717697638402

104/

https://twitter.com/jposhaughnessy/status/1320548196020604929

116/ Superforecasting: The Art and Science of Prediction (Tetlock, Gardner)

https://twitter.com/ReformedTrader/status/1326234446668812288

117/ Thomas Kuhn's work on the history and philosophy of science was conducted at around the same time as the seminal work on behavioral economics:

https://twitter.com/ReformedTrader/status/1331998734276653059