The best predictor of future performance is past performance. But unless you’re promoting from within, you don’t have past performance to evaluate. The employment interview can help predict future performance, but only if you use it well. It also has to meet legal requirements.

Asking certain questions during an employment interview violates the law. You cannot ask questions about a candidate’s health background or workers’ compensation history. You cannot ask about age, religious beliefs, dependents, personal habits or hobbies, or arrest record. To pass legal muster, you may ask only questions that directly relate to the job that’s open and available. Even some questions that may be relevant to the candidate’s ability to do the job are illegal.

The point of the interview is to acquire information. Specifically, you want answers to three questions: Can the candidate do the job? Will she do the job? Is there anything that might prevent her from doing the job?

The first question pertains to qualifications. You want to be sure the candidate is qualified to do the job you have open. The next question relates to the candidate’s general attitude and willingness or motivation to do the job. The last question relates to subjects like health problems, legal issues, dependency problems, or other factors that could prevent the candidate from doing the job even if qualified and motivated.

To get the answers to these three questions—and you usually have only about an hour—you must structure the interview to induce candidates to reveal themselves. Don’t ask questions that waste time or provide irrelevant information, such as “Why don’t you tell me about yourself?” And avoid statements that a candidate can anticipate, such as “Tell me about your strengths and weaknesses.” Prospects can predict such exchanges and will provide a prepared answer.

The best (and legal) questions are ones that address the candidate’s judgment and experience relative to the tough issues that will arise. You want to know how the person will handle the situations that keep you up at night. Skills such as sales techniques can be taught, but qualities such as integrity can’t. In structuring the interview, consider the three or four toughest situations that the job holder will face. Imagine the toughest customer situation that is likely to crop up. Think of the dilemmas that occur relating to quality versus time or following the rules or making the customer happy. Present the situation and tell the candidate to put herself in that situation and say what she would do. If she gives good answers, ones that demonstrate experience or judgment, then you have a winner. If you get weak answers, don’t make a job offer.

A few examples may be helpful.

You could ask the candidate, “If invited to take the position, when would you be available to start?” If the candidate is currently working and says he can start tomorrow, then he has just cheated his employer out of a notice period. If he’ll do that to his current employer, he’ll probably do that to you when he leaves. This demonstrates lack of integrity. If an applicant says she can start after giving two weeks’ notice, you might follow up with, “That’s great, but I’m kind of in a bind; can you start tomorrow?” If she agrees, she’s revealed herself. The candidate who insists on giving proper notice to the current employer is demonstrating integrity.

Tell the candidate to imagine himself in this situation: He’s been employed at your store for six months. Your policy is that the store stays open until 7:30 p.m., and employees are required to stay till 8:00 p.m. to put the jewelry away. You’re away at a convention and the candidate and one other senior employee are on duty. At 7:30 p.m. the candidate locks the doors and begins to put away the merchandise. The other employee grabs her coat, says “See you tomorrow,” and leaves him to do the work and lock up. He notices that she has written 8:00 p.m. as her clock-out time. What would he do?

You should also present a scenario that relates to the candidate’s ability to deal with customers. First, think about a recurring problem you’ve had with customers in the past, such as rudeness or indecisiveness, then devise the scenario. For example, ask the candidate to consider a customer who is looking at three different pendants and can’t make up her mind. One is too expensive for her but he thinks she’d like it best. The other two are more affordable but not as classy. Ask the candidate what he would do.

You know what you would do in this situation, and you know what you’d want the employee to do in your absence. If you hear that answer or another good answer, then you have a winner. If not, you might still hire, but you’d know the person will require more training and more time to grow into someone who meets your needs.

The questions asked during the interview should be as tough as the job itself. Candidates who can’t handle the interview won’t be able to handle the job. Hiring is a big decision. Considering the length of time an employee could be with you and the costs associated with a bad hire, you could be making a million-dollar decision based on the one or two hours you spend interviewing. If you’re not satisfied with the candidates in the pool, keep looking. Remember, a bad hire is far worse than no hire.

The interview is about getting information, not giving it. The more you talk the less information you’ll receive. The candidate should talk at least 75 percent of the time. There will be plenty of time later on to discuss the store and your policies.