PDF Summary:Don't Trust Your Gut, by Seth Stephens-Davidowitz

Instead of stumbling blindly through existence or turning to self-help gurus for advice, can’t our modern, technological age provide a more scientific toolkit for life? Maybe so—in Don’t Trust Your Gut, Seth Stephens-Davidowitz argues that if we use “big data” to analyze the outcomes of millions of people’s life decisions, we might finally determine which of the many choices we make have the greatest impact on success and happiness.

In this guide, we’ll explain the benefits of big data—how it can guide us and how it reveals that some decisions don’t really matter. We’ll lay out how making choices based on data can help improve your romantic life, your chances of advancing in your career, your effectiveness as a parent, and your overall happiness. We’ll also explore the limitations of big data, potential flaws in its assumptions, and differing views on the nature of self-improvement.

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The Numbers on Success

Just as hard data can give you the tools to be rational in your pursuit of love, it also acts as a guide to financial success. According to Stephens-Davidowitz, researchers working with anonymized taxpayer data have determined that more than 80% of the richest people in the US are those who started a business. However the data also reveals that popular beliefs about entrepreneurship are wrong, that the road to wealth is long and boring, and that your odds of achieving runaway financial success are highly dependent on which field you enter.

(Shortform note: Stephens-Davidowitz doesn’t claim that starting a business is an automatic path to wealth—he’s clear that only some businesses are successful, as we’ll cover later in this section. What he doesn’t bring up are business failure rates—according to the US Bureau of Labor Statistics, less than 35% of businesses survive for more than 10 years. Agriculture businesses have the highest longevity rates while those in the mining sector fare the worst.)

The Real Entrepreneurs

Stephens-Davidowitz describes the popular myth of entrepreneurship this way: A brilliant young person drops out of college, starts a company in their parents’ garage, invents some genius product that industry insiders would never dream of, and becomes an overnight millionaire. This rarely happens, but when it does, the media latches on to it and milks it for every ounce of drama it’s worth. As a result, all we hear are stories of young, maverick business founders to the point that we believe they’re whom we should emulate.

(Shortform note: The myth that Stephens-Davidowitz criticizes is what Malcolm Gladwell calls an “overstory”—an overarching narrative that shapes how society thinks. In Revenge of the Tipping Point, Gladwell explains that an overstory—such as the myth of the brilliant, renegade entrepreneur—doesn’t come from leaders and policy makers, but instead is driven by popular culture and the beliefs of large groups of people. Overstories can be useful or harmful, depending on how they frame society’s problems and what they encourage people to do.)

Despite the myth of the young entrepreneur, the data tells a different story. Stephens-Davidowitz writes that after crunching the numbers on nearly 3 million entrepreneurs, two facts stand out:

1. Your chances of being a successful business founder increase with age. Tax data shows that the average person behind a successful new business venture is well into their 40s. The young, daring entrepreneurs of legend are outliers, not the norm.

2. Your chances of success are double if you already have experience in your field. Like the value of youth, the premise that innovative business plans only come from outside an industry is bunk. For the most part, to have a groundbreaking idea, you have to know and understand what’s been tried before.

What Is Entrepreneurship?

Stephens-Davidowitz writes about entrepreneurship and starting a business as if they’re the same, but renowned business management expert Peter Drucker disagrees. In Innovation and Entrepreneurship, he argues that true entrepreneurship involves creating new markets, not just copying what others have done. Drucker is also clear that entrepreneurship isn’t confined to business startups—it takes place within established businesses as well.

While Drucker agrees with Stephens-Davidowitz that knowledge of a field is crucial for innovation, he points out two barriers that come with it. The first is inertia—if you think you know what success looks like based on past experience, you’ll be tempted to pursue the old way of doing business instead of trying something new. The second is ego—once you’ve established a successful business, you need to know when to step back and let it run.

Stephens-Davidowitz connects the prevalence of older entrepreneurs to their deep understanding of their business fields, but there may be another reason why seasoned professionals make good entrepreneurs—they have a better understanding of what it takes to manage a business. Drucker argues that what sinks many startups isn’t their lack of innovative ideas, but their inexperience with business management. The older you are, the more likely you’re aware that a startup can’t be run by the founder alone and that you need to establish a strong management team to bring your new business to market.

Therefore, Stephens-Davidowitz argues that big data’s message is clear: To increase your odds of business success, spend the time to fully master your field before trying to start your own company. This may sound obvious, but the more exciting (if spurious) narrative of entrepreneurship has permeated the business world to the point that we now have to back up common sense with hard numbers.

(Shortform note: Though Stephens-Davidowitz highlights the importance of your individual expertise, a thriving new business is rarely a one-person operation. In Zero to One, billionaire Peter Thiel states that the most important decision you’ll make when founding a new startup is who will do it with you. For your business to survive, you’ll need a strong team and a unifying culture that leverages everyone’s knowledge and skills, not just those of the founder.)

The Unromantic Side of Business

In addition to discussing age and experience, Stephens-Davidowitz highlights studies showing that certain categories of businesses produce the most wealth for individual owners—and unfortunately, they’re not very glamorous. To increase your odds of becoming rich through your business, you’ll want to focus on (in no particular order) car sales, market analysis, real estate, financial investing, and wholesale distribution. None of these are businesses that spark many people’s ambitions when they’re young. Nevertheless, these are the paths that statistically provide the most return on investment.

(Shortform note: Stephens-Davidowitz’s advice to follow a “boring” path to business success assumes that wealth is your only goal. However, in Reboot, entrepreneur Jodie Fox insists that there’s value in following your passion, even if your business doesn’t work out. Passionate people work harder, spend more time finding innovative solutions, and are generally more attractive to customers and investors. The alternative to following your passion—doing uninspired work that you dislike—can leave you feeling trapped and depressed.)

Beyond the numbers, Stephens-Davidowitz suggests that these profitable businesses share two things in common—they’re relatively immune to competitive price wars, and they’re in industries that aren’t monopolized by multinational giants. The reasons vary from industry to industry: Some are highly localized, some rely on specialized knowledge, and some have legal protections from competition. In each case, these businesses benefit from structural barriers that statistically decrease the odds of defeat by small-business Davids or corporate Goliaths. As much as you may dream of starting some other type of business that aligns with your passions, the data says that if you want wealth, this is the way to achieve it.

(Shortform note: In Innovation and Entrepreneurship, Drucker acknowledges the same benefits of niche monopolies that Stephens-Davidowitz describes, but he argues that they’re rare and offer limited potential for growth. Drucker suggests two different paths to success: You can corner a new market with an innovative product or, better yet, let someone else try it first then outfox them by identifying a market that they’ve missed—as when Apple took the concept of a point-and-click computer interface from Xerox and aimed it at home consumers.)

The Numbers on Raising Children

In addition to finding love and success, many people dream of starting a family, yet once they have children, many worry that they’re doing too much or too little to raise them right. However, Stephens-Davidowitz says that statistical studies on parenting methods reveal something unexpected—that most of the parenting choices people make have very little impact on their children’s development. Nevertheless, there are two exceptions that do have a measurable impact on children’s success as they grow up—where you choose to raise them and, if they have athletic aspirations, which sports you help steer them to.

(Shortform note: In Cribsheet, Emily Oster adds a point of nuance to Stephens-Davidowitz’s claim that parenting decisions have little impact, based on research data. She says that the problem with parenting research is that it’s hard to design studies in a way that shows causality, which makes their results difficult to translate into actionable advice. As an alternative, she suggests that you use economic reasoning to weigh the risks and benefits of parenting decisions, based on what data you can find about their outcomes.)

The idea that parenting styles are unimportant might be hard for many people to believe. And yet, Stephens-Davidowitz states that when looking at statistically significant numbers of children, big data research supports the strength of genetics in the “nature versus nurture” debate. To differentiate between inborn and environmental factors, scientists study identical twins who grow up apart and families with multiple adopted children (who are genetically dissimilar but share the same upbringing). The numbers reveal that the decisions parents make—from what to feed them, how much screen time they’re allowed, to how strict you are about their grades—have only a marginal impact on children’s success in adult life.

(Shortform note: In The Blank Slate, cognitive psychologist Steven Pinker details research that mostly backs up Stephens-Davidowitz’s assertions, stating that when twins raised apart are tested for traits like intelligence and neuroticism, about 50% of each trait is shown to have a genetic origin. However, some researchers have critiqued the model used to arrive at that number. Other studies found that how children perceive their relationship with their parents, such as whether they feel their parents are proud of them, impacts the extent to which genes influence their personalities, putting the heritability of certain traits at a range of 20%-76%.)

The Community Effect

However, the numbers reveal that one factor has an oversized effect on your children’s development—where they grow up. Not only does it matter what city you raise your child in, but researchers can now determine which individual neighborhoods are best for children. Of all the possible reasons, Stephens-Davidowitz argues that the most compelling is that by choosing where your children are raised, you determine what adult role models they’re exposed to. For example, neighborhoods with many college graduates produce more children who go on to college. Some neighborhoods are better for low-income families—for instance, if they provide role models who succeed despite their financial struggles and are active in their communities.

(Shortform note: The neighborhoods Stephens-Davidowitz discusses are rich in what social scientists call social capital—the positive value of in-person networks, community bonds, and friendships. In Bowling Alone, Robert D. Putnam shows that places with high social capital also have high rates of educational achievement, good mental health, and upward economic mobility. Unfortunately, his data also shows that social capital in the US has sharply declined since the 1950s and places where high social capital can be found are becoming few and far between.)

In short, Stephens-Davidowitz argues that as long as you’re making an honest effort as a parent, don’t stress about your day-to-day decisions. However, if you’re concerned about your children’s upward mobility, visit the Opportunity Atlas, which organizes the neighborhood research mentioned above into a guide to help you find where to best raise your children.

(Shortform note: One limitation of Stephens-Davidowitz’s analysis is that his only measure of parenting success is how much income children later make as adults. In The Gardener and the Carpenter, psychologist Alison Gopnik argues that approaches like this are flawed because they prioritize a desired outcome instead of creating a supportive environment. Gopnik recommends a gentle parenting style, but other psychologists recommend an approach that’s warm but demanding, noting that children raised in such a way seem to have the best outcomes in terms of happiness, self-esteem, school performance, and mental health.)

How to Pick a Sport

The other decision—which children often make themselves—that adults can nonetheless help to encourage is what sports they might choose to go into. Not all children aspire to be athletes, but for those who do, Stephens-Davidowitz suggests that big data can help determine the most likely path to athletic success. Once again, the question comes down to nature versus nurture—or in this case, genetic predisposition versus the willingness to train and work hard. Does a person have to be a born athlete, or can they learn to be one through effort? The statistical answer turns out to be “it depends on the sport.”

(Shortform note: One factor of sports success Stephens-Davidowitz doesn’t cover is that culture determines many children’s athletic path. For instance, in The Sports Gene, David Epstein points out that culture and economics can explain why some sport-specific talents seem to cluster in certain areas, such as Kenya producing so many marathon runners. In Kenya, the prize money from a large marathon is a fortune for the average citizen, so while the same athlete may be good at basketball, training for track and field makes more economic sense.)

Stephens-Davidowitz points to research that tracks different siblings’ athletic success. The numbers show that some sports require the right genes to reach the top, while others are open to anyone willing to learn. Basketball, running, and swimming favor certain genetic traits and body types that align with the mental skills needed for the game, whereas in baseball and football, the genetic factor is smaller. Studies of siblings who qualify for the Olympics reveal that diving, weightlifting, and horseback riding reward effort and training over natural talent more than any other sport. So, as a parent, if your child has aspirations but isn’t “built” for athletics, you might gently guide them to sports they might find more fulfilling.

(Shortform note: The genetic component of athletics isn’t as simple as Stephens-Davidowitz suggests. According to the field of epigenetics, having the right genes isn’t enough because a person’s lifestyle and environment determine how those genes are expressed. For instance, a child may have the basketball gene, but if they grow up malnourished or with little exercise, their bodies won’t develop into their full potential. Epigenetic studies on sports show that the relative impact of genetics (nature) and environment (nurture) is still difficult to untangle.)

But what does it matter what sport a child goes into? Stephens-Davidowitz argues that professional aspirations notwithstanding, athletic scholarships open many doors to college education. If your child is willing to pursue such a path, a statistical analysis of college admissions reveals which sports offer the greatest opportunities. The most popular sports are, of course, very competitive, and the average high school athlete’s chances for a scholarship are low. However, several less obvious choices offer greater odds because the ratio of scholarships to applicants leans more heavily in a student’s favor. These include gymnastics, fencing, and hockey for boys, and rowing, horseback riding, and rugby for girls.

(Shortform note: The trouble with Stephens-Davidowitz’s “less obvious sports” is that most of them have financial barriers to entry or are only available at elite private schools. In Revenge of the Tipping Point, Malcolm Gladwell examines the relationship between college admissions and less popular athletic fields. What he finds is that young athletes in these sports mainly come from white, affluent families who can afford to have their children participate. Gladwell suggests, therefore, that some schools disproportionately recruit for these sports as a form of “reverse affirmative action” to make enrolling rich white students easier.)

The Numbers on Being Happy

So far, all the parts of life we’ve covered—love, success, and parenting—reflect an even larger goal—the desire to simply be happy. Once again, Stephens-Davidowitz argues that big data can offer a guide to happiness by correlating what people do and how they feel on a massive scale. He finds that certain behaviors tend to bring us down while others objectively improve our spirits, suggesting that the path to happiness isn’t that complicated at all.

In this case, the data Stephens-Davidowitz refers to comes primarily from the Mappiness smartphone app, which prompted millions of willing participants to record their daily activities as well as their emotional states. The result was a gigantic pool of information that data scientists have been able to mine so they can answer, scientifically, how to be happy.

(Shortform note: The happiness data collected by Mappiness is 100% self-reported, but while Stephens-Davidowitz accepts it at face value, other researchers question to what degree people can accurately measure their mood. For instance, Gallup polling data shows that women report higher levels of overall happiness than men, but when asked about specific life circumstances, the tables turn and they report less happiness than men. Psychologists have other tools beside self-reports—they can measure biological responses and behavioral indicators, such as changes in hormone levels or how often people smile. However, these tools are hard to use outside the lab and their results are uncertain for various reasons.)

Why We’re Miserable

The reason we need data to tell us about happiness is that the human brain is notoriously bad at determining what will make us happy or not. Stephens-Davidowitz points to specific mental errors discovered by psychologist Daniel Kahneman that warp how we remember our emotions and thus how well we can predict them. The first is that our brains ignore how long an experience lasts, pleasant or otherwise. The other is known as the “peak-end rule,” which states that when we look back on an event, we judge whether we were happy or not by how we felt at the most intense moment and how we felt at the end. As a result, our memories are skewed, so we need to look at data collected during happy and unhappy times as they happen.

(Shortform note: While rooting out what makes us happy is Stephens-Davidowitz’s focus, it wasn’t the direct aim of Kahneman’s research. Instead, Kahneman sought to overturn the prevailing economic theory of his time, which claimed that people make decisions based on reason and probability, not emotion. In The Undoing Project, Michael Lewis recounts how Kahneman and his research partner, Amos Tversky, proved that human beings are far more irrational and emotionally driven than economists had previously believed.)

What the numbers reveal is that we spend most of our time doing things that objectively make us unhappy, such as chores, driving to work, and worst of all, work itself. According to Stephens-Davidowitz, work ranks at the bottom of the happiness scale, with nothing but illness listed as more unpleasant. For most of us, work is a necessity, and one might argue it leads to happiness later because of the money you earn. However, the research Stephens-Davidowitz cites is clear that money’s effect on happiness is very slight—you’d have to increase your salary by a lot to increase your happiness even by a little.

(Shortform note: Stephens-Davidowitz accepts these rankings at face value, which assumes that certain actions and events cause unhappiness. However, this may not be so. In Happy, Derren Brown illustrates this through the lens of Stoic philosophy, which says that happiness and suffering don’t result from what happens to us, but instead come from the stories we tell ourselves about those events. According to Brown, if you blame work for your unhappiness, that’s an internal judgment you’re making and not an intrinsic property of your job.)

Stephens-Davidowitz also explains that we’re often wrong about what types of recreation make us happy. In the Mappiness data, “relaxing” pastimes such as watching television, playing video games, and reading books produced fewer feelings of enjoyment than expected. Meanwhile, scrolling through social media produces a decidedly negative effect on happiness—Stephens-Davidowitz references one study that showed that the best way to benefit from social media is to quit it. Doing so improves your emotional state in a way that’s comparable to therapy.

(Shortform note: Though Stephens-Davidowitz connects “less enjoyable” recreation activities by virtue of their passive nature, there is another point of view. In Digital Minimalism, Cal Newport contends that our constant engagement with technology has led to a widespread decline in mental health due to “solitude deprivation.” He writes that when we spend less time alone with our thoughts, we miss out on the important benefits of quiet time, such as enhanced creativity, self-reflection, and problem-solving. Newport touts the emotional and cognitive value of taking a break from all outside input, which, like Stephens-Davidowitz’s list, includes reading books.)

How to Have a Good Time

Thankfully, there’s good news to go along with the bad. Analysis of the Mappiness data as well as other studies concur that there are clear and relatively direct ways to improve your overall happiness. In general, what the top-ranked happiness-boosting activities have in common is that they involve being active in some way, rather than the passive forms of recreation mentioned above.

(Shortform note: In addition to active engagement, there’s another common thread to the activities below that Stephens-Davidowitz doesn’t mention—they all evoke feelings of wonder and awe. In Awe, Dacher Keltner writes that of all the primary emotions, wonder is the one that quiets the ego, fosters togetherness, and gives life meaning. Though not always enjoyable—you can feel awestruck by a catastrophe—your sense of wonder ties your individual experience to something bigger than yourself, sparking creativity, community, and often joy.)

1. Sexual intimacy easily tops the list of things that make people happier. Therefore, the data-driven methods Stephens-Davidowitz provided earlier to empower you in your romantic life may arguably have the largest impact on your life satisfaction overall. (Shortform note: Despite its high ranking on this list, sexual desire tends to decline over time in most relationships. In Mating in Captivity, Esther Perel says this is normal, and that if you want to rekindle desire, it’s better to focus on the quality of your intimacy rather than just how often you have sex. Finding ways to make sex creative and playful is more effective than simply turning up the frequency.)

2. Cultural events and demonstrations, such as concerts, theater performances, and museum exhibits, are next on the happiness list. While these may not seem “active” at first glance, Stephens-Davidowitz points out that they all involve more deliberate engagement than staying home and staring at a screen. (Shortform note: There may be a deeper evolutionary reason why events and exhibits increase happiness that Stephens-Davidowitz overlooks. In What Is Art For?, Ellen Dissanayake argues that in the distant past, the arts probably helped our species to survive by making daily activities pleasurable while preserving cultural knowledge.)

3. Physical exercise and other active hobbies scored higher in the happiness data than study participants expected. Stephens-Davidowitz attributes this discrepancy to the energy cost these activities carry, but once you engage in them and afterward, your happiness undergoes a measurable boost. (Shortform note: In Energize, Simon Alexander Ong confirms that exercise releases mood-lifting hormones, but unlike Stephens-Davidowitz, he admits that physical activity won’t lift your spirits if you dread it. Therefore, he recommends finding forms of exercise that you actually like and giving yourself a variety of options so that you don’t feel stuck in a routine.)

4. Socializing with others boosts happiness, but with a certain caveat—not all social interactions are created equal. Stephens-Davidowitz explains that socializing’s effect on happiness depends on how strong your relationships are. Spending time with loved ones and friends gives you a stronger boost than interacting with strangers. (Shortform note: These cautions about socialization are especially true for introverts. In Quiet, Susan Cain explains that while extroverts thrive on stimulation from social activities, introverts find such activities exhausting—they greatly prefer one-on-one conversations, as well as spending time alone.)

5. Being outdoors improves happiness, especially in conjunction with any other activity on this list. (Shortform note: Nature’s mood-boosting effects can be attributed to the outdoors acting as a biological release valve. In The Nature Fix, Florence Williams argues that since we evolved in natural environments, urban life comes at a biological cost, such as ever-present noises that keep our bodies on alert and diminished access to sunlight that causes vitamin D deficiencies. Not only do natural settings remove the stressors of city life, but spending time outdoors improves cognitive function simply by relaxing our overtaxed minds.)

Compounding Happiness

To make things even better, Stephens-Davidowitz argues that happiness is additive, so combining different pleasurable activities magnifies their impact. In other words, if attending a concert makes you happier, attending a concert with friends does even more. The Mappiness data backs up this argument by correlating people’s reported mental state with what they’re doing, where they are, and who they’re with. This compounding effect also helps alleviate situations that make you unhappy. For instance, being sick isn’t quite as terrible if you have a loved one with you giving support.

(Shortform note: If happiness adds up, as Stephens-Davidowitz suggests, does that mean it’s easy to combine pleasurable activities? It might be, if you exploit the Diderot Effect—a psychological phenomenon in which acquiring one possession triggers the acquisition of more. In terms of fiscal responsibility, this is usually seen as a negative, but in Atomic Habits, James Clear explains how you can hack this common mental reaction for your benefit. Clear shows how you can use it to stack good habits atop one another, linking a new behavior you want to a current habit you engage in. If you employ Clear’s “habit stacking” approach to create behaviors that make you happy, then you can use happiness to build more happiness.)

Stephens-Davidowitz concludes by suggesting that being satisfied with your life isn’t as hard as we often make it out to be. Happiness, after all, doesn’t come from dramatic but fleeting life events, achieving great success, or becoming really rich. According to the numbers, happiness comes from living an active life, finding things to do outdoors, and sharing our time with friends and those we love. While none of this is shocking news, he says, we have such a bad habit of looking for joy in the wrong places that we need data science to remind us of the truth.

Happiness in the Real World

Though Stephens-Davidowitz makes happiness sound easy, it may be fair to say he’s left out some variables. In The Happiness Hypothesis, Jonathan Haidt suggests a more nuanced formula, stating that happiness is a function of your affective style (S), the conditions of your life (C), and your voluntary activities (V)—or H=S+C+V. Some factors in the formula are out of your control, such as your biological baseline for happiness (S), while the conditions of your life (C) are partially in your control, and your activities (V) are yours to do with as you will. It’s the latter that Stephens-Davidowitz highlights, but it’s not the only contributing factor.

Another unavoidable variable is suffering—sooner or later, things in life go wrong, and if happiness is simple, so is its opposite. If Stephens-Davidowitz’s happiness advice isn’t enough to cover every circumstance, you might consider cultivating joy as a backup plan. In The Book of Joy, the Dalai Lama and Archbishop Desmond Tutu take care to distinguish between happiness, which depends on circumstances, and joy, which comes from within. Joy shapes how you view happiness and suffering, that which you experience and that which others feel. While they don’t provide “hard data” on joy, Tutu and the Dalai Lama insist that joy, not happiness, is the one emotion that explores what’s best in the human experience.