Today’s missive covers three of our favorite subjects: innumeracy, psychology and investing. It comes to us courtesy of an article in Outside magazine discussing “the epidemic behind selfie deaths: 259 people died between 2011 and 2017.” The article goes on to document some of the risky and foolish things people did while taking a selfie before they were killed, usually by falling from someplace very high.

The article brought to mind shark attacks, which we fear inordinately even though they so rare that they amount to little more than statistical rounding errors. Meanwhile, we pay almost no attention to mundane but much more lethal threats, such as heart disease and cancer, which claim many, many more lives than sharks, selfies, lightning strikes, terrorists or any of the other freakish events that kill people. Not that you could tell this based on news report or the postings on social media, but the grim reality is that you are something like 35,000 times more likely to meet your maker due to the former than one of the latter.

We fear the bizarre and emotionally resonant, not the commonplace or ordinary. For example, in 2018 there were nine selfie deaths in the U.S. and one fatal shark attack. Meanwhile, the Centers for Disease Control reports that about 610,000 people die each year of heart disease, the No. 1 killer, and almost the same number die from cancer.

Let’s try to put these numbers into an accurate frame of reference, and avoid the usual denominator blindness. That is the practice of quoting a single number while omitting any context; in other words, the numerator without the denominator, the two figures needed to give you a percent or fraction.

The epidemic of selfie deaths described by Outdoor magazine was a tragedy involving 259 people who died in a six year period. Divide that figure into the number of years when those death occurred and you get an average of about 43 death a year. That's the numerator.

What of the denominator? To create that, we need to come up with a credible estimate of the number of selfies taken each years.

At Google’s I/O developer conference in 2014, we got this interesting data point: We take an average of 93 million selfies every day. And that is just on Android phones; add in iPhones and other operating systems and it has to be way over 100 million daily selfies. And that was five years and a few billion smartphone sales ago.

The fuller picture now looks something like this: There are billions of cell phones in use today. They take trillions of photographs annually. By my very inexact calculation, we take about 36.5 billion  selfies a year. So stuff those numbers into the calculator and the share of people who die while taking a selfie works out to 0.000000001182648 percent.

The parallels to investing are obvious: We fear rare events like stock-market crashes and hyperinflation, when we should be focused instead on the mundane, like broad diversification and keeping costs low. To be more specific, our attention is captivated by black-swan events like the 1987 market crash, when the Dow Jones Industrial Average plunged a record 23 percent in one day; this is metaphorically akin to a terrorist attack, while high fees that erode long-term returns are more like elevated LDL cholesterol.

We are all susceptible to these kinds of cognitive and behavioral errors. As Outside correctly pointed out, “Our species evolved as hyper-social creatures uniquely concerned about how others perceive us.” We are obsessed with what everyone else is doing — whether it's taking a selfie that leaves others in awe or fear of missing out on the next hot investment, be it Amazon, Bitcoin or house flipping or whatever. Fear of missing out is simply that old Wall Street saw of fear and greed by another name.

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