Broadening the Mind Part II: Basing Decisions on the Bell Curve

Rationally speaking, people should make decisions based on sound, scientific evidence, especially when it comes to policy. The No Child Left Behind Act was one example of such “evidence-based education,” which was supposed to integrate professional wisdom with solid empirical evidence in making decisions about how to deliver instruction. Though its focus on accountability is laudable, The Department of Education’s limited focus on performance (students and teachers) displays an alarming ignorance of the conditions required for real learning and achievement to take place, especially if innovation is the 21st century goal.

A similar parochialism seems to also afflict the government (as well as pundits and the general public) in other areas of policy (e.g., economic, social, public health, and foreign), which reflects America’s identity struggle dating back to its inception. Essentially, there have always been two conflicting interpretations of the American ideals of freedom and democracy. On the one hand, the founding fathers (such as Franklin, Hamilton, and Madison) were polymaths who felt that the health of democracy depended on an educated citizenry; this perspective reflected their Enlightenment upbringing. The other segment believed too much education might produce an inequality that would violate the very democratic ideals that education was supposed to foster, reflected in part by the rising influence of fundamental evangelism at the end of the revolutionary era. It viewed excessive devotion to learning as a secular threat that would interfere with or contradict biblical exegesis and serve as an obstacle to personal salvation. (Richard Hofstadter’s Anti-intellectualism in American Life and Susan Jacoby’s The Age of American Unreason traced the roots of the American ethos — religion and secularization, democratic ideology, and the idealization of the self-made man — to explain America’s current decline. Also read my previous post on this topic, Tracing the Roots of our Malaise.)

Scientific conclusions, though, can be just as capricious as one’s intuition. Recently, two surprising health studies questioned the validity of vitamin supplements. The first one, known as the SELECT study, found that participants receiving Vitamin E had a 17% increased risk of prostate cancer. The second study, which examined the effects of multivitamin on older women, found an increased risk of dying of cardiovascular disease and cancer. Both conclusions contradict long-held beliefs about the benefits of vitamins and only serve to make beneficial choices even more maddening. So what rule of thumb can we use to aid in decision-making, especially when it involves contrasting scientific evidence?

Consider the bell-curve.

As many people are aware, the bell-curve is a theory of probability in statistics that explains how things in life are distributed. Under normal circumstances, everything generally falls into this distribution in the following fashion: the majority of cases comprise the middle, sandwiched by a smaller minority at the top (the exceptional) and the bottom (the worst). If considering income distribution, the largest portion of people would fall in the middle class, with a much smaller portion that are either wealthy or destitute. Almost everything else in life and in nature that can be measured falls into this normal distribution, including academic achievement, intelligence, political views, and physical size. Statistically, about 68% tends to fall in the middle (as depicted in the figure below as green), 28% comprises the blue portions on opposite ends of the middle (14% each side), and finally 4% represent the yellow at the extreme top and bottom (or left and right, depending on your perspective). This roughly accounts for 100% of cases. The bell curve is a relative indicator of trend, or where we stand.

So how can this help us be better decision-makers?

If one study has a significant and new finding, do not accept it as truth yet. The same can apply if one person asserts an unorthodox statement; much like the exceptional 2% found in bell curves, it could be an exception or anomaly. If two or more studies (or people) have similar conclusions, start to pay attention. And if even more studies arrive at the same conclusion, it is safe to assume its validity for the most part, since it is no longer the exception. In other words, look at the entire body of evidence on the topic, not just one study (or even two). Once its conclusion is echoed enough times, it will fall into the 68% majority distribution, where it is pretty much accepted as fact, much like long-established conclusion of the dangers of smoking.

Let’s look at health studies on cell phone radiation as an example. There are currently mixed conclusions; some say the danger is unwarranted as long as emitted radiation is below federal standards, but more than a few studies have pointed to health concern. I for one would heed its warnings. Same with recent studies asserting the hazards of the standard American diet (SAD) — one that emphasizes meat and dairy to the detriment of vegetables, fruits, and grains. It is certainly enough to warrant a change in eating habits. New studies always start at the extreme ends of the bell-curve, but move towards the middle as subsequent studies validate its conclusions. This is why observing the overall trend is so crucial to making better decisions; trends can be fickle. Finding where it is on the distribution scale is the key.

The applicability of the bell curve is not just limited to research; it can be applied to every aspect in life: What political candidate should I vote for? What is the healthiest way to eat or exercise? What’s the best way to raise children? How do I make myself stand apart from all the applicants? The answers are surely complex, but seeing the broad range of answers (whether through online search, professional consultation, etc.), helps one to discern consistent themes that are echoed or validated.

Following the bell-curve is not the same as advocating for moderation, however. Though such conventional wisdom is part of this blog’s raison d’être, moderating one’s perspective only considers the degree of action (or inaction), but not whether something should be done in the first place. For example, the rule of moderation may help one decide how much to exercise or to drink, but not whether or not to try drugs. The bell curve, with its inclusion of outliers, can account for the percentage of those who have not tried them as well as how much for those who have.

The bell curve is also not the same thing as following the majority, though there can be wisdom in numbers. The majority can be mislead and is sometimes wrong, especially when it is isolated. An adolescent who is pressured to smoke by his circle of friends needs to step outside his perspective to see the folly of the crowd. A Los Angeles teen whose peers consider plastic surgery as “no big deal” should explore other segments of the country and world where it’s never even heard of. Sometimes the majority perspective can even be too conventional, requiring inspired thinking. The bell-curve accounts for this diversity — the whole 100% distribution. It includes seeing and acknowledging the anomalies and outliers (the 4% extremes), as well as the other segment (the still substantial 28%) that falls outside of the majority. Ironic how understanding the bell curve can allow one to see, for example, the parochialism of popular culture (or the masses) for what it really is.

Despite the above concerns, recognizing the majority 68% can also be comforting. Within the din of contemporary American politics, where media coverage has been devoted to the extremes of Tea Party politics on the one end and Occupy Wall Street protesters on the other, it is reassuring to know that Americans are quite moderate in their political views for the most part; that both personal responsibility and public support is needed to raise America from its recent woes. 81% believe America is on the wrong track, 71% believe the country is in decline, and 89% believe that politicians should compromise on major issues like the deficit than take a hard line, according to a Time poll. It’s the same reason why a good economy rests on a robust middle class. (Read more about this silent majority in Joe Klein’s Middle of the Road.)

The bell curve is a constructive guide, but for it to work effectively, there has to be three considerations. First, the source of information must be valid; hence why respected research journals are peer-reviewed and subject to random sampling. If they are not, there is potential for bias. It is also why credible researchers and journalists triangulate their data by checking different sources — via inquiry, observations, and third party interviews.

Second, one should always maintain a healthy dose of skepticism, no matter how well a scientific finding is established. This general mindset, which philosopher Bertrand Russell advocated for in collection entitled Sceptical Essays, is at the root of objectivity.

Third, when confronting ambiguity, one should strive to follow “the flow of nature.” If one is unsure about the validity of conclusions drawn from cell phone radiation studies, for example, then perhaps looking at what is done in nature can inform us; in this case, machine usage is probably best kept to a minimal. What about eating a vegetarian diet compared with an omnivorous one? This goes back to the aforementioned American diet; a tougher question to answer, as all kinds of eaters exist in nature.  However, looking at the longevity of turtles and other herbivores might point us towards a more whole-foods diet that relies less on meat consumption.

In the end, the bell-curve is a heuristic tool. By considering all the possible answers that lie on the bell curve, one can discover the most optimal decision to make. Sometimes it means following the majority, and other times the minority. That self-discovery is what broadens the mind.

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