Education Markets

I'm always impressed by the faith libertarians, and some contrarian liberals, put into education markets. They speak of them in the rapturous tones of Bill Kriston contemplating slaughter, or me talking universal health care. But none of the evidence I've seen on charter school outcomes has been very convincing. My understanding is that while they've not cream-skimmed, taking only the rich and white as some Democrats feared, they've failed to improve outcomes among their students. Nor have they been found to improve the performance of surrounding public schools -- a RAND study (pdf) said there was "no measurable impact" and "no evidence that charter schools create a competitive environment." But surely the libertarians have seen these studies too, and I've spent very little time studying education policy. So please, someone, show me what I'm missing, or have to read, or where the compelling evidence lies.