A common theme in Hawai'i when education is discussed is this: If the private schools can do it, why can't the public schools?

This reflects the perception that private schools generally do a better job, overall than the public schools. In some cases, this argument leads toward a discussion of vouchers.

There are some obvious responses: First, private schools can be selective while public schools must take all comers. Also, private schools generally enjoy students from motivated families, and motivated families translate directly into better-performing students. Private schools also generally have a much freer rein in discipline policies.

But now a new study suggests the argument of public vs. private may be much more complicated and nuanced.

The report completed for the U.S. Department of Education concludes that the difference in educational achievement between public and private schools is much less dramatic than critics tend to believe.

The study used results from the 2003 National Assessment of Educational Progress (the national "report card") in math and reading for fourth and eighth graders. Thousands of public schools and hundreds of private schools were studied.

When the raw scores are compared, private schools do statistically better in math and reading at both grade levels. That's as expected.

But when the authors of the study controlled for such things a gender, race, socio-economic status, status as an English-learner and others, a different picture emerged.

Based on adjusted figures, the average for public schools was significantly higher than the average for private schools for grade 4 mathematics. Meanwhile, the average for private schools was significantly higher than the average for public schools for grade 8 reading after adjustment.

Score one for public schools (grade 4 math) and one for private schools (grade 8 reading). The other two categories were a wash.

Now the authors are quick to caution that this study is a national study that does not take into account specific conditions in individual school districts. It also notes that private schools tend to draw particular kinds of youngsters.

Still, the bottom line here is that public schools can and do compete well with the private sector. The answer for some seeking even more improvement is not to abandon the public schools — but to work with them to make them even better.