[Phil153]

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Car A and Car B both hold a 4 star rating from Phil's rating agency. When you read the rating you see that they measured two metrics, gas efficiency and trunk space. You then further learn that Phil's rating agency called up the manufacturer of Car A and told them that they would be basing their ratings exclusively on gas efficiency and trunk space. Would you go around telling people that these two cars were "equal"?

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I get the point of your argument, there's no need for simplistic analogies. What you've failed to do is provide evidence that excessive test gaming is causing a significant increase in the public schools scores and not in the private schools.

And you're also missing the point that both public and private schools are scoring poorly on this test, worse than public education systems in other countries. The bottom line is that private schools are doing a piss poor job as well.

Another independent metric is SAT scores. It's hard to get exact information, but the common number reported is that private schools typically score 100 points above public schools on a 2400 point scale (around 4% better, or 6% if you take the average of 1700). This is more or less in line with the 3% (based on total possible points) we see in the previously quoted data. Given that these schools attract an upper demographic, and that they contain the set of resource rich, upper level prep schools, there really is little indication that private schools in general do better on these metrics.

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The existence of public schools as they are makes it harder for private schools to access resources

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How so? Millions of children attend private schools - more than enough for a full scale economy. As I stated above, the private school market in the US is equivalent to the full or half market size in smaller coutries. Are you saying that a certain market size is needed for this to work? Seems strange to me.


Your point about public schools attracting more talented teachers due to higher wages is plausible. They certainly have more qualified teachers, on average. But private schools offer many benefits, better conditions and much higher job satisfaction, so I'm not sure how large this effect is.

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If you are going to write a textbook for fifth graders you are going to focus on the curriculum that has a potential 90% market share, not a 10% one.

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The textbook market is saturated already - people are more than happy to write for a multi million child niche. There's such a low barrier to entry in this market that I don't see it. Even my high school teacher wrote a high quality physics textbook in his spare time. And that's for Australia which is 1/15th the size of the US.