> But they do not point out that their bias is for libertarian causes. Had they not found that more libertarian states perform well by their measure, they would

> But they do not point out that their bias is for libertarian causes. Had they not found that more libertarian states perform well by their measure, they would never have published this. The first statement is true. The piece would be a bit stronger if the researchers noted that by publishing in Reason, they're at the very least giving the appearance of potential confirmation bias. Your second statement makes an unsupported assumption though. RE: SAT scores - not all students take the SAT, some students take it multiple times, the SAT is taken at different points in time per student, and it's a test that is so influential in college admissions that success on it is strongly correlated with wealth, as scores are best improved by tutoring on test taking strategy, not increasing general knowledge. I agree that grade 4 and 8 are probably not optimal to get a complete picture of education quality, but there is no reward to the student for doing well, so they're less likely to have spent substantial time investing in beating the test.