The act of answering survey questions can increase awareness, which opens the door to development.

Editor’s note: This article is part of a new MIT SMR series about people analytics.

“Know thyself.”
— Socrates

I’ve been studying grit for 15 years, but the notion that some people stick with things much longer than others is not at all new. A century ago, Stanford psychologist Catherine Cox studied the lives of 301 eminent achievers. Cox concluded that the artists, scientists, and leaders who change the world have a striking tendency to hold fast to their goals and to work toward these far-off ambitions with dogged tenacity.

Picking up where Cox left off, I wanted to see whether grit — the combination of passion and perseverance toward long-term goals — would predict achievement in the 21st century. I was curious about how this aspect of our character relates to age, gender, and education. I wanted to unpack grit’s motivational, behavioral, and cognitive underpinnings. In short, my aim was to study grit scientifically. To do so, I needed to measure it.

Why are scientists like me obsessed with measurement? In the immortal words of Lord Kelvin: “When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the stage of science, whatever the matter may be.”

That is, a valid measure illuminates what you’re trying to understand, and understanding is the whole point of scientific inquiry.

Questionnaires are one way to assess personal qualities like grit. Performance tasks, informant ratings, biodata, and interviews are alternatives. But in psychological research, in part because of their low cost and ease of administration, self-report questionnaires are far more common.

The disadvantages of asking people to rate themselves are obvious. You can, if you’re motivated, fake your way to a higher score. You may interpret the questionnaire items differently than other people. You might hold yourself to higher (or lower) standards. The list goes on.

But self-report questionnaires have unique advantages, too. Nobody in the world but you — not your boss, your best friend, or even your spouse — has 24/7 access to your thoughts, feelings, and behavior. Nobody has more interest in the subject (you) than yourself.