The decision by Japan's education ministry to make public the average scores of annual nationwide achievement tests on a prefecture-to-prefecture basis will have consequences that threaten educational quality. At least that's the lesson to be learned from Los Angeles.

Ever since the accountability movement began in California 14 years ago, public schools in the state have published their Academic Performance Index. This index distilled standardized test scores into a single number. It's the rough equivalent of an average score.

But because the API did not take into account graduation and attendance rates or consider science, history, the arts and physical education, it has wisely been put on hold for a couple of years while California introduces the Common Core standards.