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How would you like someone using a snapshot of a few minutes to judge your personality, skills, and ability to do a job?

Unfortunately, that’s the reality of hiring. You can collect lots of data about people who want to work for you: information about their accomplishments, their experience, their performance on tests you design. But face time with candidates is always going to be limited.

A good interview question, though, can help you learn as much as possible in the shortest amount of time. Which is why I love the following question, which I learned from fellow author Suzy Welch:

What did you do to prepare for this interview?

“I myself have used this query for years,” says Welch. “And, oh, the answers I’ve heard–the good, the bad, and the ugly–and always so revealing.”

For example, how about the woman interviewing to be Welch’s executive assistant?ADVERTISING

“I’ve been stalking you for three days,” she replied.

But that “stalking” turned out to be impressive; it included reading Welch’s two books and everything else she could find online, so the candidate could get a better sense of Welch’s personality and discover ways she could add value.

“As a result,” says Welch, “she came to the interview ready to talk not just about her fit for the requirements of the job–but my interests, values, and, perhaps most impressive, the intellectual content of my life’s work.”

Another candidate had prepared an extensive analysis of Welch’s profiles on social media, along with a critique recommending what Welch should change or refine. This candidate even evaluated the apparent marketing plans for Welch’s new book’s launch, which led her to form a list of questions for Welch–enough to fill a full page.

Of course, the answers aren’t always so extraordinary. (“I read your Wikipedia page,” replied one particularly underwhelming candidate.)

But that’s what makes this interview device so great. With a single question, you can:

  • Find out whether the candidate has a learning mindset
  • Get an idea of how the person approaches problem solving
  • Gain insight into the individual’s personality
  • See how important this job is to the person

Best of all, you’ll see a real-life example of the level of preparation the candidate is willing to put forth for an important project.

Because, let’s be honest: If someone didn’t prepare well for the interview, can you expect the person to prepare for anything else?

Enjoy this post? Check out my book, EQ Applied, which uses fascinating research and compelling stories to illustrate what emotional intelligence looks like in everyday life.

A version of this article originally appeared on Inc.com.