Reruns of The Celebrity Apprentice notwithstanding, firing people is not much fun. It's costly, too: studies show that firing and replacing an employee costs anywhere from thousands of dollars to two times the employee's annual salary. That's why you want to be sure you are making smart firing decisions.

But aside from the obvious cases (I'm thinking of you, Bill O'Reilly), how do you know if and when you should fire an employee? Kim Scott offers some savvy advice on that very topic in her new book, Radical Candor: Be A Kickass Boss Without Losing Your Humanity (St. Martin's Press, March 2017). Scott, an entrepreneur who did stints at Google and Apple before founding training consultancy Candor, Inc., says that before you fire someone, you should ask yourself three questions.

Have you given the employee radically candid guidance?

A good boss-employee relationship requires radical candor, according to Scott. To employ radical candor, you must care personally about employees and you must challenge them directly when their work is not up to par. So, the first question you need to ask yourself before firing someone is whether you have done everything you can to help the employee make the grade.

Have you made the employee aware, asks Scott, "that you care personally about her work and her life, and have you been crystal clear when you have challenged her to improve? Has your praise been substantive and specific about what she has done right, rather than simply a salve to her ego? Have you been humble as well as direct in your criticism, offering to help her find solutions rather than attacking her as a person?" If you can't answer yes, maybe you've fallen down on the job, not your employee.

How is the employee's poor performance affecting the rest of the team?

The shortcomings of poor performers affect everyone else who works for you. So, the second question ensures that you consider the full cost of a poor performer on the overall business before you call him into your office.

Scott learned this lesson the hard way after launching her own company, Juice Software. She hired "Bob," who looked great on paper, but didn't live up to his résumé on the job. Scott liked Bob and couldn't bring herself to fire him--until she realized that her indecisiveness was having a ripple effect. "Others on the team wondered why I accepted such poor work," she recalls. "Then they began to wonder if I knew the difference between great and mediocre; perhaps I didn't even take the missed deadlines seriously. As is often the case when people are not sure the quality of what they are doing is appreciated, the results began to suffer and so did morale." Scott answered the second question, but it was too late: Juice Software failed not long after she fired Bob.

Have you sought out a second opinion?

Being objective about your own decisions and communication skills is hard, and firing people has organizational and legal ramifications. So, the third question is meant to confirm that you have spoken to someone whom you trust and with whom you can talk the problem through before you fire an employee.

"Sometimes you may think you've been clear when you haven't been," explains Scott. "Getting an outside perspective can help you make sure you're being fair. Also, if you don't have experience firing somebody, talk to somebody who does." Better than a law suit, no?