Book excerpt: Choices matter. And in your teens and twenties, some of the biggest life decisions come about when you feel the least prepared to tackle them. Economist Robert T. Michael won’t tell you what to choose. Instead, he’ll show you how to make smarter choices. Michael focuses on five critical decisions we all face about college, career, partners, health, and parenting. He uses these to demonstrate how the science of scarcity and choice—concepts used to guide major business decisions and shape national legislation—can offer a solid foundation for our own lives. Employing comparative advantage can have a big payoff when picking a job. Knowing how to work the marketplace can minimize uncertainty when choosing a partner. And understanding externalities—the ripple of results from our actions—can clarify the if and when of having children. Michael also brings in data from the National Longitudinal Survey of Youth, a scientific sample of 18 million millennials in the United States that tracks more than a decade of young adult choices and consequences. As the survey’s longtime principal investigator and project director, Michael shows that the aggregate decisions can help us understand what might lie ahead along many possible paths—offering readers insights about how their own choices may turn out. There’s no singular formula for always making the right choice. But the adaptable framework and rich data at the heart of The Five Life Decisions will help you feel confident in whatever you decide.