Take a look at the site, everything is listed, including education levels, continuing education, and experience. Plus, it is a government site so you can not dismiss it as right wing. Public school teachers outstrip private school teachers across the board. And most private school teachers do not get benefits.
I don't disagree, but I think if you were to be able to look at demographics and compare marital status, length in career (private v. public schools), certifications, and education you would also find some interesting indicators.
IMHO they would be that more often private school teachers have a working spouse and are not the sole source of family income and medical benefits, they less often make it a "career" as there is less provided for long term financial security and lack of health benefits, that significant percentage are working until they can get a public school job, that many schools do not require certification or comparable education backgrounds.
I mention that because my sister was a private school teacher for about 5 years. Pay was about half of a public school teachers, no benefits, and retirement options. She loved the smaller classes and the kids, but she had no choice but to go public to support herself, make a dent in student loans, and begin to plan for her future.
On top of that, private schools consistently outstrip public schools in academic performance, graduation rates, college placement, and graduation from advanced studies courses.
Correlation though does not equal causation. (Hmmm - did I get that right?)
1. Private schools are not required to take all "comers" like public schools are.
2. Private schools can forgo taking on special education students and their associated higher costs (and typically poorer academic performance).
3. Private schools can screen students for academic performance and reject those that don't meet entrance standards.
4. Private schools can expel students for poor academic performance (artificially raising their record of academic achievement).
5. Private school can require certain levels of parental involvement which contributes to student performance.
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Not disagreeing with what you said, just pointing out some other factors.
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