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Like predictive judgments, evaluative judgments entail an expectation of bounded disagreement.
Evaluative judgments partly depend on the values and preferences of those making them, but they are not mere matters of taste or opinion.
the boundary between predictive and evaluative judgments is fuzzy and people who make judgments are often unaware of it.
System noise is inconsistency, and inconsistency damages the credibility of the system.
It may seem paradoxical to claim that we can improve judgments when we cannot verify whether they are right. But we can—if we start by measuring noise.
in professional judgments of all kinds, whenever accuracy is the goal, bias and noise play the same role in the calculation of overall error.
a key feature of MSE: squaring gives large errors a far greater weight than it gives small ones.
Error in a single measurement = Bias + Noisy Error
Overall Error (MSE) = Bias2 + Noise2
In terms of overall error, noise and bias are independent: the benefit of reducing noise is the same, regardless of the amount of bias.
MSE conflicts with common intuitions about the scoring of predictive judgments. To minimize MSE, you must concentrate on avoiding large errors.
specify the roles of predictive and evaluative judgments in decisions. A widely accepted maxim of good decision making is that you should not mix your values and your facts. Good decision making must be based on objective and accurate predictive judgments that are completely unaffected by hopes and fears, or by preferences and values.
System Noise2 = Level Noise2 + Pattern Noise2
Simply put, just like a basketball player who never throws the ball twice in exactly the same way, we do not always produce identical judgments when faced with the same facts on two occasions.
Averaging two guesses by the same person does not improve judgments as much as does seeking out an independent second opinion.
if you can get independent opinions from others, do it—this real wisdom of crowds is highly likely to improve your judgment.
If you cannot, make the same judgment yourself a second time to create an “inner crowd.”
regardless of the type of crowd, unless you have very strong reasons to put more weight on one of the estimates, your best bet is to average them.
People who are in a good mood are generally more positive.
mood has another, more surprising effect: it also changes how you think.
a good mood makes us more likely to accept our first impressions as true without challenging them.
People who are in a good mood are more likely to let their biases affect their thinking.
The propensity to find meaning in such statements is a trait known as bullshit receptivity.
Inducing good moods makes people more receptive to bullshit and more gullible in general; they are less apt to detect deception or identify misleading information.
we need to emphasize an important truth: you are not the same person at all times. As your mood varies (something you are, of course, aware of), some features of your cognitive machinery vary with it (something you are not fully aware of).
If you are shown a complex judgment problem, your mood in the moment may influence your approach to the problem and the conclusions you reach, even when you believe that your mood has no such influence and even when you can confidently justify the answer you found.
the gambler’s fallacy: we tend to underestimate the likelihood that streaks will occur by chance.
you are not always the same person, and you are less consistent over time than you think. But somewhat reassuringly, you are more similar to yourself yesterday than you are to another person today.
the moment-to-moment variability in the efficacy of the brain is not just driven by external influences, like the weather or a distracting intervention. It is a characteristic of the way our brain itself functions.
social influences create significant noise across groups.
In politics, as in music, a great deal depends on social influences and, in particular, on whether people see that other people are attracted or repelled.
In short, political positions can be just like songs, in the sense that their ultimate fate can depend on initial popularity.
“chance variation in a small number of early movers” can have major effects in tipping large populations—and in getting both Republicans and Democrats to embrace a cluster of views that actually have nothing to do with each other.
social influences are a problem because they reduce “group diversity without diminishing the collective error.”
The irony is that while multiple independent opinions, properly aggregated, can be strikingly accurate, even a little social influence can produce a kind of herding that undermines the wisdom of crowds.
informational cascades. Such cascades are pervasive. They help explain why similar groups in business, government, and elsewhere can go in multiple directions and why small changes can produce such different outcomes and hence noise.
informational cascades make noise across groups possible and even likely.
there are two problems. First, people tend to neglect the possibility that most of the people in the crowd are in a cascade, too—and are not making independent judgments of their own.
Second, informational cascades can lead groups of people in truly terrible directions.
Information is not, of course, the only reason that group members are influenced by one another. Social pressures also matter.
with social pressure cascades: people might well exaggerate the conviction of those who have spoken before them.
Across groups, social influences also produce noise.
Very similar groups can end up in divergent places because of social pressures.
group polarization. The basic idea is that when people speak with one another, they often end up at a more extreme point in line with their original inclinations.
Internal discussions often create greater confidence, greater unity, and greater extremism, frequently in the form of increased enthusiasm.
Looking at the same case, deliberating juries were far noisier than statistical juries—a clear reflection of social influence noise. Deliberation had the effect of increasing noise.
Not only were deliberating juries noisier than statistical juries, but they also accentuated the opinions of the individuals composing them.
In business, in government, and everywhere else, cascades and polarization can lead to wide disparities between groups looking at the same problem.
deliberating groups tend to be noisier than statistical groups that merely average individual judgments.
Since many of the most important decisions in business and government are made after some sort of deliberative process, it is especially important to be alert to this risk. Organizations and their leaders should take steps to control noise in the judgments of their individual members. They should also manage deliberating groups in a way that is likely to reduce noise, not amplify it.
