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Try finding test scores in science for public schools, you can't find large scale random samples of public schools for these test, they don't exist.
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Read this:
http://nces.ed.gov/nationsreportcard...es/2006459.pdf
This is a comprehensive assessment of public and private school performance in science in 2000. It shows exactly the same kind of differences we see in other metrics such as reading and mathematics. So your point is dead.
Also note other interesting information in that chart: private schools have higher levels of white children (
who score significantly higher in school), as well as higher rates of parents who have completed college, far fewer children with disabilities and far fewer English learners. All are strongly correlated with performance.
So I repeat again something which you seem to want to continue debating: Private schools as they exist now do just as terribly, on average, at educating students, in the three largest metrics. This is despite all their inherent advantages (smaller class sizes, more personalized attention) and the existence of significant competition and many other free market drivers already (even if they aren't as comprehensive as you'd like). Science scores from the PDF above:
Now, you can throw all this data out and say "but a totally free market will be different." Borodog goes as far to claim that the problem will be "easily" solved. Where is your evidence??? You don't like the evidence I provide, but I'm trying to discuss the evidence that is available. You do understand that evidence is the key part of a rational debate, don't you?
Also, claiming that SAT stats are a poor metric seems rather strange to me. SAT tests are good enough for private colleges of America to use as half of their admissions criteria. The fact is that reading and math proficiency are a good guide for the quality of the school you went to, as they're the basis for most other subjects. And since the science results show the same trend...claiming that reading and math are being focussed on (and that this is responsible for the clos result between public and private schools), is simply wrong.
As far as your points go, I do not agree with these two:
Public schools have significant incentives in the metrics used to compare public V private that private schools don't have
Public schools admit to decreasing time in classrooms for those courses not measured
You are generalizing. I'm pretty damn sure that private schools have incentives for their students to do well on the SAT - way more than public schools, in fact. Yet they don't do very much better - and no better at all when you adjust for the different demographics. And the fact that science scores show the same differential invalidates your point IMO.
I also don't agree with the seller's monopoly point. Private schools offer significant benefits (smaller class sizes, longer holidays, more job satisfaction - as determined from teacher surveys) that would offset many of these pure $ considerations.
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Can you find statistics showing that private school attention to these subjects are also declining at similar rates?
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You haven't shown statistics for the rate at which public school education is declining on these subjects...