YOU WOULD think that Gov. Corbett had come up with some intriguing new data to justify plundering public-school budgets for voucher money.

Or that all those voucher advocates who marched on Harrisburg last week to support a voucher initiative introduced by Sens. Jeffrey Piccola and Anthony Hardy Williams knew something the rest of us

don't.

In fact, the only thing that has changed in the 15 years since the last attempted raid on the public treasury failed is the fact that it is now politically palatable. Corbett campaigned on a pledge to resurrect vouchers from the dead. He's just keeping his promise.

In 1996, voucher advocates were rebuffed by experts who predicted that the transfer of tax money would deplete funding in already-underfunded public schools. The public was not ready for that trade-off.

Today, Corbett couldn't care less.

"They're either going to downsize or they're going to get competitive and vie for the students," Hizzoner declared.

But this whole voucher business is a faith walk. There is no credible evidence that the achievement of public- or private-school students has been improved by the availability of vouchers.

But the advocates are still reading from that old testament.

"Parents," Harrisburg Assistant Superintendent of Schools Sybil Knight Burney said last week, "are the ultimate accountability standard."

Really?

She might want to read "Fixing the Milwaukee Public Schools," a report of the nonpartisan Wisconsin Policy Research Institute, a longtime choice advocate.

The October 2007 report showed that only 10 percent of Milwaukee's public-school parents have been the "active consumers needed . . . to exert market-based influence" on public schools.

Local parents, the report said, "simply do not appear engaged enough" to ensure the desired outcomes.

It's been 20 years since I went to Milwaukee to look at America's first full-blown voucher program.

Democratic Wisconsin state Rep. Annette "Polly" Williams had gone toe-to-toe with teachers' unions and others who opposed her proposal to allow public-school parents to move their children and tax dollars to the schools of their choice. She beat them all.

The state assembly allowed Milwaukee parents to take $2,500 of the state's $4,500-a-year per-pupil subsidy and spend it on any school they chose. Within weeks, "private" schools opened in some of the buildings left empty by the collapse of Milwaukee's parochial-school system. It looked promising even to me.

Before the results of the first achievement tests were published, Williams was on the circuit, appearing at Harvard, Yale and other universities. The New York Times, no less, named her one of 13 innovators who changed education in the 20th century.

But all it really changed was where Milwaukee's public-school dollars got wasted. The district's public and voucher schools have fallen further behind other state schools in reading and math achievement.

After 16 years, the Policy Research Institute was talking about the limits of parent-driven reform.

"Relying on public school choice and parental involvement," it concluded "may be a distraction from the hard work of fixing the district's schools."

But it is the distraction of choice. Congress funded a voucher program that provided up to $7,500 per pupil for Washington, D.C., public-school students. Three years later, 1,700 voucher students had achieved "only modest improvements" in reading and "no measurable improvement" in math, according to the U.S. Department of Education.

Despite this, House Speaker John Boehner is pushing Congress to save the funding, which is slated to expire this year.

And in Harrisburg, Senate Bill 1 would divert $7,200 from the state's education budget for every pupil who chose to go to a private or parochial school. The bill would also add $25 million a year to a fund that offers tax credits to companies that invest money in students who transfer to private schools.

With the state facing a possible $5 billion budget shortfall, where do you think that money would come from?

It will be drawn from the same source that has funded seven consecutive years of improvement in test scores in Philadelphia.

Maybe it's time to get a few busloads of parents up to Harrisburg to advocate for that.

Send e-mail to smithel@phillynews.com or call 215-854-2512. For recent columns: www.philly.com/ElmerSmith