A parent knows more about her child than any elected official or government bureaucrat ever could.

It’s a simple, straightforward concept. But it often gets lost in political debates surrounding parents’ role in choosing the best education for their children.

A recent conversation with Nicole Stelle Garnett helped remind this observer about the importance of parental insights. Garnett is John P. Murphy Foundation professor of law at the University of Notre Dame. She’s also an adjunct fellow at the Manhattan Institute. She wrote a recent MI report on accountability in private-school choice.

“Research evidence about private school performance suggests that private school choice ‘works,’ in terms of test scores, but not all,” Garnett told me. “But the gains in test scores are marginal.”

That doesn’t sound like a strong endorsement of parental school choice. But there’s more.

“The long-term gains are really substantial,” she added. “So if you participate in a private school choice program, you are likely to graduate from high school, go to college, persist in college, have a job, not go to prison.”

“I think all of that suggests that parents know things,” Garnett concluded. “We academics might think, ‘Oh, they’re making bad decisions. They’re not really paying attention to the test scores.’”

But if long-term benefits of private school choice are so strong, then an intense focus on test scores alone makes little sense. It’s unfortunate for students, families, and taxpayers that test scores offer the primary tool government uses to judge school choice’s effectiveness.

“For many parents, academic quality as measured by test scores is not the primary reason why they choose schools in private school programs,” Garnett said. “They value school culture. Often they value religious instruction. They value safety. They value discipline.”

Since parents “know things” about their kids and what will make them successful adults, accountability for private school choice needs to focus on more than tests. Garnett’s report offers two “guiding principles” for policymakers as they consider accountability.

“Accountability regulations should encourage — or, in some cases, require — the disclosure of the information that parents need to make good decisions for their kids,” Garnett says of her first principle. “That means that they should be readily available, transparent, and easy to understand.”

Flexibility in testing aligns well with her recommendations. “I don’t support — as a condition of entering the school choice program — forcing private schools into the state accountability regime, forcing them to take the state tests,” Garnett said. “For a variety of reasons, private schools — good ones — object sometimes to state tests.”

“But they should have to take a test that’s nationally recognized, research-based,” she added. “Disclose the information to parents about how the kids at their school are doing. And they can also disclose other things that matter to parents.”

Disclosure would help parents make better choices. “I would love to see a regime where schools are encouraged to develop and disclose alternative measures of school quality, along with some test scores,” Garnett said.

The second guiding accountability principle also focuses on parents. It would increase their access to good choices. “The goal should be in private school choice … more and better schools,” she said. “That means we want to encourage the best schools [to participate].”

“If you think about it from the school perspective, the schools who really need ‘choice’ the most are often the ones with the empty seats,” Garnett said. “The ones who need the financial resources the least are probably the really strong academic ones. They have lots of paying customers that are middle-class or above. They don’t really need what is usually pretty small scholarship amounts in these programs.”

“We want the best schools to enter, so we need to make sure we don’t deter their entry by overregulating,” she added. “We need to be careful about regulations that threaten their religious liberty or autonomy of the schools.”

With more options available to parents, the people who “know things” about individual kids will have a better chance to choose options that fit those children best.

“The primary way that school choice works is we encourage good schools to provide a good education, and we let parents have the information that they need to choose among good options,” Garnett said.

As in many other areas of life, more choices lead to better outcomes. That should be the goal reformers and policymakers pursue.

Mitch Kokai is senior political analyst for the John Locke Foundation.