Data source: Programme for International Student Assessment (The Washington Post)

Today is a big day for people who care about education. Every three years, an organization called the Programme for International Student Assessment (PISA) tests 15-year-olds around the world on reading, math and science. Its latest report just came out, comparing the standardized test's 2012 results across 60 countries and four cities.

The map up top shows the average test scores for each country or city. Bluer countries have higher average scores; redder countries have lower scores. Purple countries fall in the middle.

First, a caveat against drawing too many conclusions from these data: The PISA report covers some very, very different countries. It's not really fair to compare cities against entire countries, since urban areas tend to outperform non-urban areas in education. And it's certainly not fair to compare rich countries that can afford lots of public education programs against poorer countries that can't, except perhaps to drive home that having a robust and well-funded government can make it easier to educate lots of students.

The lowest average national score is Peru's, at 1155. The highest average scores are in city-sized East Asian areas: Shanghai (score of 1762), Singapore (1667) and Hong Kong (1661), in that order. The top-ranked countries are also East Asian: South Korea, Japan and Taiwan, also in that order. The United States is the 25th-ranked country with an average score of 1476, behind much of Western Europe.

While much of the coverage focuses on the gap between the United States and other developed countries, looking at the results on a map drives home that it's not quite as bad as it sounds. The U.S. and a number of other Western countries are clustered fairly closely together. It sounds bad to say that the U.S. is ranked five places behind France; it sounds less bad when you look at the data and see that the average U.S. and French total scores are 1476 and 1499, respectively. That's pretty similar.

Scores are significantly lower in developing countries that participated in the study; that's true in most of Latin America and in all Middle Eastern and Southeast Asian countries (save for Singapore) where students were tested. For all the attention paid to the gap between East Asian and Western test scores, the gap is much wider between Western and developing-economy students -- in many cases twice as wide. That's probably the starkest trend when you look at the data as a whole.