Even though there’s an almost sure-fire way to determine if your child is ready to stay home alone, most parents are loath to pursue it. That’s because it involves asking your child questions that begin, “What would you do if….”

“ …you smelled smoke?”

“…you heard a noise upstairs?”

“…the toilet overflowed?”

“…you felt lonely?”

You get the idea. Why would we want to ask a question that might plant scary ideas in our kid’s head? Scary ideas in our own heads, for heaven’s sake!

Here’s the answer: “If your child is frightened of something in the abstract, you’ve got a pretty good idea of how quickly things could fall apart in a real emergency,” says Ellen Gannett, director of the National Institute on Out-of-School Time (NIOST) at Wellesley Centers for Women at Wellesley College. Her institute specializes in researching what makes it safe for a child to be home alone. Not surprisingly, in an emergency, the ability to apply theory to practice is a big deal.

Gannett and her colleague, Kathy Schleyer, director of training and quality improvement at NIOST, agree that if you ask a child a “what-if” question and he reacts in a way that tells you he’s frightened, he’s likely already had the thought, or at least, something like it. By helping develop a strategy — “Well, what do you think you could do?” — you not only alleviate the unspoken fear but also help him build confidence in his problem-solving skills.

As for the fear that you’re planting ideas, if he’s frightened in the abstract, you need to know. It will be reassuring to him for the two of you to develop coping skills.

Only a few states legislate the age at which a child can be left home alone but the ages are all over the place — in Illinois, it’s 14; in Maryland, 8; in Oregon, 10. That’s quite a range, and it lends credence to Gannett’s next point: “It’s maturity, not age, that determines when a child is ready to be home alone,” she says. To determine readiness, she also recommends asking yourself:

What’s the neighborhood like? Are neighbors available during the day or night? Can your child identify who they are? Does she even have a relationship with them? How would she reach them? If she had to get out of the house in an emergency and those neighbors weren’t home, what’s the backup plan?

How often is he left alone? “Regularity, or lack of it, is a big factor,” Gannett says. “If home alone is your default child-care arrangement and it’s happening every day, you need to consider what opportunities are being lost.” She ticks off a few: lost social connections with peers, lost interaction with caring adults who offer positive role models and lost opportunity to learn new skills. If affordability is the reason to leave a child home alone, subsidies, grants and scholarships may be more available than you realize.

What’s your child’s personality? Some kids are so eager to please that they say what they think we want to hear. A child who’s very social may not admit that he’s lonely and miserable. Will that make him prone to temptation, like inviting kids over, or to leaving the house? Speaking of temptation: What about screens? “Most kids will default to sitting in front of a screen even when there’s a rule about them,” says Gannett. “What is he watching when you aren’t home? Equally importantly, what is he munching? Home alone on a screen can be a recipe for gaining weight.”

What’s his track record with rules? Some kids don’t do well following directions while others are prone to panic in the face of the unexpected. Will she call 911 because she can’t find her shoes (don’t laugh; it has happened) or, at the other extreme, be too timid to call if the toaster catches fire? Does your family have a safety plan for emergencies? Formulate one together. It may be educational just to hear what your child says constitutes an emergency.

“Have a few trial runs,” urges Gannett. Start off with 20 minutes and work up to an hour. Evaluate together: How did you each feel? Part of a child’s sense of safety comes from knowing she can talk to you about her fears. If you pooh-pooh them — “Oh, don’t be silly, that’s nothing!” — you risk her feeling isolated. If you overreact — “You were supposed to call me at 4:15. I rushed home, I was so worried!” — she could lose her footing.

Even after all this soul-searching, Gannett returns to the “what-if” questions. “You can learn a lot from them,” she insists. What if you call from the car to say traffic is awful and you’ll be 20 minutes late? “Twenty minutes? No big deal,” she may tell you. Great! Just to be safe, though, have her spend 20 minutes alone in the house.

Barbara F. Meltz is the former parenting columnist for the Boston Globe. She is author of “Put Yourself in Their Shoes, Understanding How Your Children See the World.”