The Importance of Outliers

Figure 1 Outlier. An Outlier is a data point or two that lie outside the norm.

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Outliers can be annoying. A single data point or two that lie outside of the norm can disrupt the mean by several magnitudes and can have a deleterious effect on statistical analysis.

They can result from human error, sampling errors, misreporting, etc. Some researchers may ignore or dismiss the outlier as noise – but the wise may see a signal in the noise: an underlying new pattern.

The story of the discovery of fluoride’s protection against tooth decay began as an outlier and later signaled a pattern (McKay, 1929). Dr. Fredrick McKay’s Colorado Springs patients were different from the rest of the population he had served. The enamel of many of his patients’ teeth was mottled with a grotesque brown substance, resembling chocolate. The condition was blamed on consuming too much pork, drinking bad milk, and something in the water. It was even more surprising to find that many of those patients were resistant to tooth decay

Figure 2. People found afflicted with Colorado brown stain (dental fluorosis) were surprisingly resistant to tooth decay.

Source: Courtesy of Olena Zaskochenko Shutterstock.

When Colorado brown stain was found in individuals from other communities, and they too were resistant to decay, it signaled fluoride’s importance in protecting teeth from decay. McKay’s 30-year search for the cause of Colorado brown stain revolutionized dental care, making tooth decay for the first time in history a preventable disease (McKay, 1929)

People like McKay, who see the world through patterns, can spark change. They see things from the outside and may have a clearer view of what is happening on the inside than the insiders. Or, at least, they will have an alternate point of view that could be especially useful or new. They can have something unique to offer. People who are not steeped in the mindset of the status quo are free to create beyond it. This is the outlier’s asset.

Malcolm Gladwell’s book, Outliers: The Story of Success, features individuals who do not fit the usual patterns (Gladwell, M. (2008). Because they stood out from the rest, as you will learn below, we discover, upon further study, that a sense of community plays a vital role in our health, birthdates decide the success or failure of a future hockey player, and a person’s ethnic background can compromise the safety of an airplane and its passengers (Gladwell, 2008).

As COVID 19 spreads around the globe, data on those who fallen ill have revealed clear patterns. Four out of five people suffer only mild symptoms. Very few children get sick. Most of those who become severely ill are old or have an underlying health condition.

Figure 3. As Covid 19 spreads around the globe, data of those who fell ill reveal clear patterns.

Source: Image courtesy of Pixabay (Gerd Altmann)

But as with any illness, there are outliers — such as young athletes who succumb, or the Connecticut newborn who died of COVID-19 even though infections are exceedingly rare in young children. Such experiences point to an enduring mystery: When a virus strikes, why do some otherwise healthy people get clobbered while others skate through (Freyer and Alanez, 2020)?

The discovery of other outliers raises similar questions (Lee, 2012): Why do certain rare individuals not only get by on little sleep but thrive on less than six hours per night? They are called short sleepers, and often have the additional traits of being energetic, upbeat, and ambitious—Benjamin Franklin, Thomas Jefferson, and Leonardo da Vinci may have been short sleepers.

And why do some individuals have perfect pitch–or ‘absolute’ pitch? Only about one in 10,000 have it and they can sing or play any note on the spot, with no previous training. Why are some individuals able to perceive a range of colors not visible to other humans? Researchers have suspected that these individuals have an extra color-sensitive retina, beyond the normal complement of three in humans.

People who see the world through patterns bring new thinking into the fold. They can show us what we have not been seeing. They may point to opportunities we were blind to. They may even reveal parts of ourselves we had not noticed.