Overpaying for a low-quality product won't turn it into something better.

Outside of politics, this isn't a controversial notion. Plopping down $20,000 for a 10-year old Kia isn't going to turn that car into a brand new BMW. If you were repeatedly dissatisfied with your neighborhood pizza joint, you wouldn't go back to the pizza shop and pay double for the same thing. Instead, you'd order Thai or otherwise find a better way to spend the take-out food portion of your household budget.

Which bring us, somehow, to the topic of early childhood education.

A new report published this week in Behavioral Science and Policy Journal, raises serious questions about whether the widespread adoption of publicly funded preschool programs is in the best interest of children and taxpayers. Dale Farran and Mark Lipsey, the two Vanderbilt University researchers who published the study, say governments are funding pre-K programs without having a good sense of what these programs should be trying to achieve and without knowing how to judge if they're working.

These programs aren't cheap. According to the Brookings Institution, state and federal governments spent more than $34 billion on pre-K last year. Head Start, probably the most well-known early childhood education program, has been around since the 1960s and it costs the federal government more than $8 billion a year—not counting the matching funds that state and local governments pay when they receive a Head Start grant.

After all that time and all that money, there's not much evidence that Head Start has given students much of a head start. A 2010 report from the U.S. Department of Health and Human Services concluded that any benefits from the program "yielded only a few statistically significant differences in outcomes at the end of 1st grade."

Still, that doesn't mean all pre-K program don't work. Oklahoma, for example, has been funding statewide early education since 1998 and boasts that 74 percent of all four-year olds are enrolled in pre-K. Studies that tracked Oklahoma students from 1998 through 2010 found that children enrolled in pre-K consistently outperformed others, regardless of class or race.

Oklahoma's successes set off a mad dash in state capitols. By the end of 2015, 54 state-funded pre-K programs were operating in 42 states plus Washington, D.C., at a cost of more than $6.2 billion for state taxpayers. Programs that used to be narrowly targeted to low income students are now being expanded—New York City recently adopted a universal pre-K program and Barack Obama called for states to do the same in his 2016 State of the Union address.

In the rush to create new programs and expand old ones, Farran and Lipsey say, states are misallocating money and not checking for results.

"Viewed with a critical eye, the currently available research raises real questions about whether most state pre-K programs do anything more than boost 4-year-olds' academic cognitive skills to where they would be by the end of kindergarten anyway," Farran and Lipsey conclude. "Children are not well served by a perpetuation of magical thinking about the likelihood of profound effects resulting from poorly defined, state-run pre-K programs."

You can think about it like this: federal and state governments are spending $34 billion annually on take-out pizza, based on a study of take-out pizza in Oklahoma that concluded take-out pizza in Oklahoma was delicious. These governments don't know if the pizza everywhere else is any good. They don't know whether they would be better off spending their money on Thai food instead. They don't even know how to decide if the pizza they are getting is any good, but they're willing to pay more for it.

Hillary Clinton is promising to join the party. The Democratic presidential nominee says she would double the number of children enrolled in Head Start and would expand other federally-subsidized programs with the goal of giving all four-year olds access to pre-K. Clinton is no stranger to the issue: in the 1990s, she pushed for an expansion of Head Start that passed during her husband's time in office.

As with many other topics, Donald Trump's view on early childhood education is difficult to ascertain. He's a firm believer in local control over schooling decisions—"I'm a tremendous believer in education. But education has to be at a local level," he bellows in one campaign ad—and he has outlined a plan to allow parents to deduct the costs of child care, but it's not clear how he views the government's role in providing pre-K (the Republican platform adopted in Cleveland opposes public funding for pre-K on the grounds that it's a government intrusion into the parent-child relationship).

Regardless of who wins the election, federal and state officials should be asking if it make sense to keep funding pre-K when even the federal government admits it can't find much evidence of success in decades of trying?

It all comes down to "the ongoing triumph of hope over experience," says Lisa Snell, director of education policy for the Reason Foundation, which publishes this website.

"There are solid reasons to remain skeptical of multi-billion dollar investments in universal preschool," said Snell. "While there is research that preschool may improve some outcomes for kindergartners in terms of language development, the long-term gains from universal preschool have been more difficult to capture."

That's true even in Oklahoma—remember, the one state that had gotten pre-K right?

Oklahoma's improved test scores in reading happened only after the state implemented a third grade retention program to hold back students who weren't reading at the appropriate grade level. New evidence suggests that policy probably has more to do with the state's recent uptick in verbal and reading skills than the state's decades-old pre-K program.

Universal preschool comes with a massive price tag. It would cost about $75 billion to implement, under the terms outlines by Obama earlier this year. States would be on the hook for about 10 percent of the start-up costs and as much as 300 percent of federal outlays by the tenth year of the program.

The New America Foundation predicts that preschool programs meeting the proposed standards would cost about $8,000 per pupil per year. At that rate, providing preschool to just 75 percent of all 4-year olds would cost taxpayers about $25 billion annually.

That's a lot of money for "magical thinking."